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Showing papers in "American Journal of Botany in 1937"



Journal ArticleDOI
TL;DR: This paper gives the figures for the root and root hair systems of a single cereal plant, Secale cereale L., which was selected because it has been used successfully in retarding erosion and also because of its importance as a grain and forage crop.
Abstract: AS AN element of the plant cover, grasses are efficient as soil binders and occupy a particularly prominent place in erosion studies. Their compact fibrous root systems develop mainly in the upper soil levels which gives them a very advantageous position in soil binding. Fortunately their economic importance as field and forage crops makes their cultivation porfitable from an agricultural standpoint as well as from one of soil conservation. The investigations by Weaver and his associates (1926) have given a general picture of the subterranean parts of many plants. Reports of these investigations deal more particularly with the horizontal and vertical distribution of root systems. A recent paper by Pavylechenko (1937) is one of the first attempting a quantitative survey of the roots of a mature plant. In this study, dealing with competition between weed and crop plants, Pavylechenko reports the total root length of several individual field grasses -namely, wild oats, 54.3 miles; Marquis wheat, 44.2 miles; and Prolific spring rye, 49.1 miles. These figures were based upon measurements of single plants grown widely separated. The survey of the root systems of these plants did not include all roots. Pavylechenko states there were "further subdivisions" which were neither counted nor measured. Had these, the quaternary roots, been included, the total figures would certainly have been much higher, probably doubling his reported totals. In general the work on root hairs has been carried on by a group of investigators whose interests have been mainly in growth responses as influenced by external factors, and apparently none of them has made a count of root hairs for an entire well-developed plant. This paper gives the figures for the root and root hair systems of a single cereal plant, Secale cereale L. Of several grasses studied in a preliminary waynamely, Andropogon furcatus Muhl., Sorgastrum nutans (L.) Nash., Poa pratensis L., and Triticum sativum L.-winter rye was selected because it has been used successfully in retarding erosion and also because of its importance as a grain and forage crop. Studies in progress deal similarly with several other grasses. The seedling of winter rye produces a whorl of four primary roots. These function for a number of weeks but disappear later as numerous permanent adventitious roots grow out from the base of the stem area and become the main roots of the plant. Branches from these are the more numerous secondary roots which in turn give rise to the tertiary

158 citations





Journal ArticleDOI
Paul J. Kramer1
TL;DR: The relation between absorption and transpiration of cut branches has been studied by several investigators and it is found that absorption lagged considerably behind transpiration in some species, but very little in others.
Abstract: THE MOST FIUNDAMENTAL phase of plant water relations in respect to effect on growth is the internal water balance or degree of saturation of the tissues. This is determined by the relative rates of absorption and transpiration. The ratio of absorption to transpiration is therefore more important than the absolute rate of either process. Rapid transpiration may not be harmful in itself if accompanied by sufficiently rapid absorption so that no long-continued saturation deficit or loss of turgidity results. On the other hand, very moderate transpiration may be injurious if the rate of absorption is very slow, as in frozen soil, and a serious saturation deficit is developed in the plant. In spite of recognition of the importance of the ratio between transpiration and absorption, very few simultaneous studies of the two processes have been made on plants rooted in soil. Vesque (1878), who seems to have carried out the first careful investigation of this problem, observed the behavior of bean and Ner-iwm plants by placing their roots in water in a potometer. He found that absorption was not always proportional to transpiration, but that usually near mid-day transpiration much exceeded absorption. If transpiration was decreased or increased by varying environmental conditions, corresponding changes in absorption soon occurred. Vesque concluded that his results supported the view that transpiration is instrumental in bringing about the absorption of water. By the use of potometers MVlontfort (1922) and Lachenmeier (1932) investigated the relative rates of absorption and transpiration of plants growing in liquid media, but they obtained rather contradictory results. Montfort found that transpiration tended to exceed absorption, while Lachenmeier found that over a period of time, both in light and in darkness, absorption exceeded transpiration. Werner (1936) developed a technique for growing plants in such a manner that the shoots could be weighed independently of the roots. He reported variations in weight of the shoot in the course of a day, which were ascribed to changes in water content resulting from inequality in rates of transpiration and absorption. The relation between absorption and transpiration of cut branches has been studied by several investigators. Lloyd (1912) reported that the transpiratio.n of cut branches of Fouqueria splendens exceeded absorption during the day, but absorption exceeded transpiration at night. Stefanoff and Stoickoff (1932) compared absorption and water loss of cut branches of a number of tree species and found that absorption lagged considerably behind transpiration in some species, but very little in others. They ascribed the variation to differences in efficiency of the conducting systems. Measurements made on cut

89 citations


Journal ArticleDOI
TL;DR: It is generally agreed that Azotobacter can assimilate nitrogen as nitrates, as ammonium salts, and certain organic nitrogenous compounds, and as orgLanic nitrogen.
Abstract: SOME YEARS AGO (1926) the author became interested in the possible effect of hydrogen-ion concentration on the assimilation by plants of nitrogen as ammonia or as nitrate. In an experiment 2 designed to attack this problem, mineral nutrient solutions containing dextrose were prepared in which the nitrogen was furnished as ammonium nitrate, ammonium sulfate, or sodium nitrate, and the hydrogen-ion concentration of the solutions was varied by intervals of 0.2 or 0.3 pH from pH 4.0 to pH 7.6. The organism used, Rhizopus nigricans, grew well at all reactions in the solutions which contained ammonium sulfate or ammonium nitrate (somewhat better in the more alkaline solutions) but not at all in those which contained sodium nitrate. This confirmed earlier reports (Bach, 1927; Ritter, 1909) of the inability of Rhizopus nigricans to assimilate nitrogen as nitrate (at least under ordinary laboratory conditions) and encouraged the writer to plan an investigation of the ability of organisms to use various forms of nitrogen. Circumstances made it impossible to carry out the investigation as planned. Nevertheless, the preliminary work may be of sufficient interest to encourage further investigations in this field. A survey of the literature (space precludes summarizing all the available literature) suggested to the author that organisms may be arranged in four groups 3 according to their ability to assimilate various forms of nitrogen. GROIJP I. NITROGEN-FIXING ORGANISMS. These organisms are capable of assimilating gaseous nitrogen and also nitrates, ammonium salts, and certain organic nitrogenous compounds. Attention should be called to the assumption that everv organism capable of fixing gaseous nitrogen is capable also of assimilating nitrogen in the form of nitrates, ammonium compounds, and 'suitable forms of organic nitrogen. Though the evidence available supports it, this assumption needs further confirmation since considerably more attention has been devoted to the relation to gaseous nitrogen of the organisms generally accepted as nitrogen fixers than to their ability to assimilate combined nitrogen. However, it is generally agreed (Waksman, 1927; Lohnis, 1926; Stephenson, 1930) that Azotobacter can assimilate nitrogen as nitrates, as ammonium salts. and as orgLanic nitrogen (for

77 citations



Journal ArticleDOI
TL;DR: Attempts have been made to discover what causes the ovary to develop into a fruit when no embryos are formed, but obviously that cannot be the explanation of the parthenocarpially formed fruits.
Abstract: PARTHENOCARPY, unlike parthenogenesis, is a term infrequently used.; yet the former phenomenon is perhaps the more prevalent of the two. Bananas, seedless grapes, grapefruit, oranges, and cucumbers may be cited as common illustrations of parthenocarpy. But these are not the parthenocarpic fruits in which the writer is interested. From numerous genetical studies we are familiar with another type of parthenocarpy. Sometimes when cross pollinations are made between species or genera, no seeds are produced, but the ovary develops into a fruit. VWhat causes these fruits to develop? Usually it is considered, perhaps without much thought, that the growth of the ovary into a fruit is the result of the development of an embryo and the resulting seed. But obviously that cannot be the explanation of the parthenocarpially formed fruits. Since 1902, when MIassart placed dead pollen on the stigma of an orchiid and observed a slight enlargement of the ovary, attempts have been made to discover what causes the ovary to develop into a fruit when no embryos are formed. In 1909 Fitting experimented extensively with tropical orchids at the Botanical Gardens at Buitenzorg. He made detailed observations on the normal responses of the orchid flowers to pollination and compared with them the responses produced when dead or foreign pollen or pollen extracts were placed on the stigma of a flower. The normal responses were a closing of the stigma, a shortening of the life of the flower, an enlargement of the gynostemium, an enlargement of the ovary, and sometimes a change in the color of the corolla. He found that mechanical injury shortened the life of the flower to about the same extent as pollination or the placing of dead pollinia on the stigma. Dead or ungerminated pollen on the stigma caused it to close, and usually a swelling of the gynostemium also took place, but neither brought about the swelling of the ovary. He made cold and hot water extracts of pollinia and found that, when placed on the stigmatic surface, extracts from some species caused a slight swelling of the ovary, but extracts from other species had no effect upon the ovary. Some of these extracts also caused color changes in the corolla. Ile further found that absolute alcohol extracts were as effective as water extracts. He found active substance only in the viscid material holding the individual pollen grains together and thouight it might also be produced in the pollen tubes; he considered it to be absent from

69 citations







Journal ArticleDOI
TL;DR: It was concluded that the degree of deficiency observable in field-grown material was not sufficient to decrease the content of growth promoting substances in shoot tips, and the relationship between mineral nutrition and growth hormone production with plants grown under controlled conditions in sand cultures was established.
Abstract: THE RELATION of mineral nutrients to the production of growth hormone in plants pertains directly to the problem of plant development. Shoot tips are the main centers of growth in higher plants; they are also the main centers of hormone production. The continuous initiation and subsequent expansion of new organs in such regions depends upon the successful mobilization of the raw materials needed for growth; likewise, the continued production of hormone depends upon the presence of the proper raw materials. Studies on the growth hormone content of Helianthus and Nicotiana (Avery, Burkholder, and Creighton, 1936) have shown (1) that the hormone is scarcely detectable in the absence of supplied nitrogen; (2) that, within certain limits, hormone concentration is in proportion to the amount of nitrate supplied to plants grown in sand culture; (3) that shoot tips of Nicotiana grown in field experimental fertilizer plots exhibit no relationship between miiieral deficiencies and hormone content. From the latter it was concluded that the degree of deficiency observable in field-grown material was not sufficient to decrease the content of growth promoting substances in shoot tips. Before further studies on this subject were undertaken, the necessity became clear for establishing the relationship between mineral nutrition and growth hormone production with plants grown under controlled conditions in sand cultures. INVESTIGATION.-Growth hormone concentration in relation to varied proportions of nutrient ions.-The relationship of growth hormone concentration to varied nutrient ion proportions was studied in Helianthus annunts L. grown in sand cultures. In this work, a nine-salt solution was employed so that it was possible to vary in any single series of solutions the concentration of any cation or anion over a wide range without extensively altering the relation of the concentrations of the ions of opposite charge to each other (Beckenbach, Wadleigh and Shive, 1936). A list of the salts employed and the amounts used for making up the different culture solutions may be found in table 1. The nine salts containing the essential elements-nitrogen, phosphorus, potassium, calcium, magnesium, sulphur-were used in amounts appropriate to yield nutrient solutions with five of the ions in arbitrary standard concentration for each series of solutions, and one selected ion was varied so as to give relative concentrations as follows: 4 times the standard, 1 (standard), 0.1, 0.02, 0.01 times the standard, and none. For example, the "4" nitrogen culture solution contained 4 times as much






Journal ArticleDOI
TL;DR: Iwanowski's filtration experiments of 45 years ago are generally regarded today as being the first demonstration of the group of infectious agents which the authors now call filterable viruses, or perhaps better, simply viruses.
Abstract: THE PLANT disease known as tobacco mosaic, which was probably first recognized by Swieten (1857), was confused with a pock disease for about 35 years. Even Mayer (1886), who published a fairly accurate description of the symptoms of tobacco mosaic, did not recognize the fact that he was working with two different diseases. He did find, however, that the juice from diseased plants was infectious and that from healthy plants non-infectious. He also reported that twice filtering the infectious juice through ordinary filter paper rendered it noninfectious. In 1892 Iwanowski announced that the mosaic and the pock disease were in reality two separate diseases, and more surprising, that the juice from plants diseased with mosaic remained infectious after being filtered through a Chamberland filter. Although he could not demonstrate the presence of an organism in the infectious filtrate, he nevertheless regarded the disease to be bacterial in nature. Beijerinck (1898) confirmed Iwanowski's filtration experiments, but chose to regard the infectious agent, not as being bacterial in nature, but, as he wrote at the time, " as a contagious living fluid." He seemed to desire to convey the idea of an unorganized material, which was capable of growth in the presence of living cells. Iwanowski's filtration experiments of 45 years ago are generally regarded today as being the first demonstration of the group of infectious agents which we now call filterable viruses, or perhaps better, simply viruses. It is significant that he chose to regard the first of these agents as organismal in nature, whereas Beijerinck chose to regard it as a new type of infectious agent. This difference of opinion which arose 38 years ago has persisted down to the present time. Is tobacco-mosaic virus organismal in nature, or does it really represent some new type of infectious agent? Chemistry, then as now, was used as an aid in studying the nature of this virus. The year after Beijerinck announced his viewpoint, papers concerned with' the effect of various chemical reagents on the infectivity of tobacco-mosaic virus beoan to apnear. The earlier investigators, including Koning (1899), Heintzel (1900), Allard (1916, 1918), and Chapman (1917), appear to have been interested in obtaining an insight into the nature of viruses by studying the effect of chemical reagents on virus infectivity. Similar work was carried out later by Birkeland (1934), Duggar (1925, 1929), Fukushi (1930, 1933), Grant (1932), Henderson

Journal ArticleDOI
TL;DR: In a study of the detailed anatomical features of the flowers it is of interest to find whether or not these classifications based on gross morphology can be supported or clarified.
Abstract: THE TAXONOMIC treatments of the Boraginaceae since the description of certain species by Linnaeus in 1773 have been many and varied. While for the most part these are regional and incomplete, even sectional treatments show clearly that the tribes and apparently many of the genera are based on tendencies and overlapping characteristics rather than clearcut differentiating characters. In a study of the detailed anatomical features of the flowers it is of interest to find whether or not these classifications based on gross morphology can be supported or clarified. The size and range of the family make it hardly to be wondered at that the taxonomic treatments are preodminantly regional. In the main, however, workers have agreed that the family is divisible into four subfamilies. A further division of one of these subfamilies into tribes is to be used in this paper. In order that the subfamilies as generally accepted be clearly understood, the following table of characteristics has been compiled from Baillon, Bentham and Hooker, Engler and Prantl, and De Candolle:

Journal ArticleDOI
TL;DR: It is shown that while marginal cells of his "third degree " type are characteristic of the young stages of all foliar structures, changes in the plane of cell division may lead to the formation of " second " and finally " first " degree types of initials.
Abstract: ALTHOUGH MARGINAL growth is characteristic of the early development of many angiospermous leaves, relatively little study has been devoted in recent years to the histogenetic aspects of this process. A critical review of the meagre literature in this field (Foster, 1936a), however, indicated a general agreement on one important point-viz., that the outermost layer of cells at the leaf margin is an independent histogen which corresponds in its growth and anticlinal plane of cell division to Hanstein's (1868) "dermatogen" and hence gives rise solely to the epidermis. Indeed, there is evidence that in certain dicotyledons the " dermatogen " and " ground meristem " at the edges of a foliar primordium arise from independent longitudinal rows of "marginal" and " submarginal" initials (Foster, 1935a, fig. 3741; 1936a, fig. 3, 5-10). The universal existence of a stabile marginal " dermatogen," however, was questioned as early as 1872 by Lund, whose neglected monograph has only recently been reviewed (Foster, 1936b). Lund (1872, p. 185-186 and 219-222, fig. 43-50) concluded from a wide comparative study of foliar histogenesis that three main types of external marginal cells (i.e., initials) exist. He characterized them as follows: (1) marginal cells of the "first degree," from which new cells are formed by walls parallel to the margin, resulting in an uniseriate border of cells; (2) marginal cells of the "second degree," from which new cells are formed by alternating, oblique, convergent walls, resulting in a biseriate layer of cells; and (3) marginal cells of the "third degree," from which new cells are formed by anticlinal, non-convergent walls, resulting in a single, continuous, external layer of cells or " dermatogen ". Lund clearly demonstrated, however, that all these categories of initial cells are genetically related in that they may arise successively during the marginal growth of one and the same foliar organ. In illustration of this, he showed that while marginal cells of his "third degree " type are characteristic of the young stages of all foliar structures, changes in the plane of cell division may lead to the formation of " second " and finally " first " degree types of initials. Complex marginal development of this sort is apparently typical of many involucral bracts, sepals, and certain bud scales. It is evident from Lund's investigations that a " dermatogen ", in

Journal ArticleDOI
TL;DR: Experiments were designed to compare the toxicity of selenites and selenates in water cultures, and the contrary evidence from the single soil experiment referred to above did not seem sufficient to controvert the reports to the effect that the selenite are the more toxic.
Abstract: IT WAS reported in an earlier publication (HurdKarrer, 1935) that wheat plants supplied with sodium selenite were less injured and contained less selenium in. their leaves than when the selenium was added to the soil as sodium selenate. In view of the fact that the selenite is the more easily reduced by organisms (Levine, 1914, 1915, 1925b), it seemed possible that its lesser toxicity might be due to its reduction to elemental selenium.Experiments were therefore designed to compare the toxicity of selenites and selenates in water cultures. There are several reports to the effect that the selenites are the more toxic (Levine, 1925a; Stoklasa, 1922; Turina, 1922), and the contrary evidence from the single soil experiment referred to above did not seem sufficient to controvert them. and selenites was checked by Dr. Lucien Greathouse, formerly of the Bureau of Plant Industry. Results obtained with those compounds found to be impure (K2SeO4 and H2SeO4) are omitted from this report. The seedlings were germinated in pure quartz sand, or on blotters moistened with distilled water, and transferred after about a week to 600 cc. widemouthed flasks containing the nutrient solutions. Three seedlings were grown in each flask, supported in holes of paraffined corks with cotton plugs. The flasks were kept in boxes, partitioned into compartments the size of the flasks, which provided partial shading of the roots. Two different series of nutrient solutions were used, having the composition shown in table 1, plus 100 cc. M/60 iron citrate in each case. The concentrations

Journal ArticleDOI
TL;DR: This report deals with the morphology of the bud and with the developmental behavior of the leaves of Viburnum rufidulum Raf.
Abstract: THE RAPIDLY increasing literature on the leaf and bud has been reviewed recently by Foster (1936a, 1928), Avery (1933), Schuiepp (1929), Zimmerman (1928), and others. The need for additional information is apparent to most workers, but there is some difference of opinion concerning the relative values of the various methods of study. Troll (1935) thought that ontogenetic studies are of relatively little valuethat the comparative study of a wide range of adult forms ("typological method") is of greater importance. On the other hand, Foster (1936a) pointed out that in developing our knowledge of the leaf " it would seem obvious that a sound and well balanced morphological treatment must attempt to relate the facts of development impartially to the form and structure of the adult organ." The " typological method " as an approach to the problem of foliar morphology is useful, but it seems that conclusions based upon such studies can hardly be considered trustworthy until comparative data concerning the growth processes of organs are assembled and correlated with the comparative studies of adult form. The value of a knowledge of the various histogenetic processes that occur in a leaf was recognized as early as 1872 by Lund, whose neglected monograph has been brought to the attention of modern workers (Foster, 1936b); and among recent investigators histogenetic studies have been and are being increasingly used in the interpretation of floral structures (Gregoire, 1935c; Newman, 1936). This report deals with the morphology of the bud and with the developmental behavior of the leaves of Viburnum rufidulum Raf., particularly with respect to the type, origin, and duration of meristems. The genus Viburnum (Tourn.) L. provides a good source of material for comparative foliar studies. Among the various species are some with highly specialized cataphylls (V. Opuluis L.), some with cataphylls lacking (V. Lantana L.), and others which seem to represent a position intermediate between these two extremes (V. rufidulum Raf., V. Lentago L.). Some species (V. Opulus) have lobed leaves with stipular appendages, others have leaves with entire margins and stipular appendages lacking. While this study will deal only with the structure and development of the foliar organs of Viburnum rufidulum, it is hoped that comparative studies can be made at an early date with V. Opulus (highly specialized cataphylls) and V. Lantana (naked buds). The researches of Cross (1937), Foster (1935a), and Schiiepp (1929) show that in some cases the foliar organs of plants with highly specialized cataphylls


Journal ArticleDOI
TL;DR: Data are presented that were obtained by methods which controlled environmental conditions and largely eliminated growth differences in the plants by a shortening of the experimental growth period to a few days.
Abstract: ONE DOES not need to delve far into the voluminous literature pertaining to mineral absorption by plants to be convinced that there are many factors which may, either directly or indirectly, affect this process. From several sources, but more recently in a paper by Hoagland and Brover (1936), it is clear that aeration, respiration, temperature, initial salts in the root tissues and culture medium, and available carbohydrates in the plant are factors concerned in the absorption of minerals. Furthermore, the importance of such factors upon mineral absorption as synthesis of foods, assiinilation, and shoot-root growth is well illustrated by the work of Gustafson (1934), Muenscher (1922), Mendiola (1922), and others. Therefore, it seems only reasonable that to measure the effects of transpiration upon mineral absorption it will be necessary to keep all of these other influential factors as nearly constant as possible. For example, in an earlier paper by the writer on this subject (Freeland, 1936) the significance of the data was somewhat obscured by inequalities in growth and dry weight of the plants. The same criticism may be made of most of the data that have been presented to date for the purpose of showing that transpiration either does or does not affect the rate of absorption of minerals. It is the purpose of this paper to present data that were obtained by methods which controlled environmental conditions and largely eliminated growth differences in the plants by a shortening of the experimental growth period to a few days. Water cultures were used to facilitate speed and accuracy in manipulation.

Journal ArticleDOI
TL;DR: It is hoped that the facts revealed in the anatomical and morphological structure of the polygonaceous flower may prove valuable in determining the relationship of the group.
Abstract: UP TO recent times the families of the angiosperms have been studied mainly from a taxonomic point of view. To some extent the morphological and anatomical aspects have been considered, but both of these mostly in a gross and external way. The observations made in such studies have been used extensively by different workers to organize a phylogenietic plan of development within the groups of flowering plants. For the most part, these observations have been incomplete and fragmentary, and interpretations of the known facts have been various. With some of the fundamental and critical facts lacking, the conclusions reached are subject to revision or verification. Much of the work does not have a firm foundation; too much has been based on hypothesis rather than on facts. If a more satisfactory phylogenetic picture of the flowering plants is to be gained, both the internal and external structure of the flowers must be studied. Not only should this study be made grossly, but also minutely. Especially is this true of the flower, the part of the plant which has been particularly emphasized in modern classification. It was not until a few years ago that much intensive work was done on internal floral morphology and anatomy. Van Tieghem, Henslow and a few others made a good start, but they were greatly handicapped in their work by crude equipment; their understanding was good but relatively rudimentary. With present-day equipment and methods, a more complete knowledge of the structure of plants can be worked out, and from the facts obtained, hypotheses, both old and new, can be substantiated or discarded. It was from this standpoint that the author began his work on the polygonaceous flower. Much work had been done on the Polygonaceae but little upon the floral anatomy. It is hoped that the facts revealed in the anatomical and morphological structure of the polygonaceous flower may prove valuable in determining the relationship of the group. FLORAL, STRUCTURE.-The Polygonaceae is generally considered to consist of about 30 genera, embracing roughly 700 species. For a family of such size and distribution, its members show unusual homogeneity in floral makeup, indicating a natural grouping. Most of the members of the group have perfect flowers, the dioecious condition appearing in a few genera only. The number of perianth parts can be used conveniently to subdivide the family into two main

Journal ArticleDOI
TL;DR: The "classical theory" (as it is often termed in current literature) of the origin of the carpel is that it was derived from an infolded foliage leaf, which is generally accepted.
Abstract: EVJER SINCE the appearance of Goethe's essay on the " Metamorphosis of Plants " in 1790, the nature of the carpel has been a leading subject of discussion among botanists. Linked as it is with the question of the origin of the angiosperms, an understanding of the carpel is needed in the construction of a natural system of plant classification. The carpel was at first studied in its external form (the method of organography), but following the classical work of Van Tieghem ( 1875), investigation has centered on its vascular anatomy. It has been found that ancestral conditions of structure, long since lost to external view, may often be represented by a lingering vascular supply. Plant vascular tissue, like the skeleton of animals, is slow to change. Only the fossil remains themselves can show more, and well authenticated proto-angiosperm fossils are yet to be found. In previous anatomical studies of the carpel, comparatively little consideration has been given to the style and stigma. Excepting the conclusions of Brown (1866), the studies of style and stigma bore little morphological import until recent years. The subject was re-opened when Saunders (1925-1934, 19281931) urged a new explanation for the commissural stigmas described by Brown. This was in connection with the theory of carpel polymorphism. Although that theory in itself has only clouded the issue (Eames, 1931), at least the attention thereby called to the stigma has served to suggest this new line of attack upon the problem of the carpel. DIsCITSSION.The "classical theory" (as it is often termed in current literature) of the origin of the carpel is that it was derived from an infolded foliage leaf (fig. 1) 2 This explanation is generally