Showing papers in "Science in 1939"

Chewing as a technique of relaxation

Abstract: charged with breeding economic plants for resistance that they must first be informed regarding the stability or limits of variability of the parasites they seek to circumvent. we know now that new7 races of fungi are arising through natural hybridization. Hybrid structures have been obtained showing dominance and Mendelian segregations with crossing-over a t reduction which is such an important feature in furthering evolution. W e also find in the fungi: mutants, lethal factors, deficient chromosomes, sex-chromosomes, sexlinked characters and other genetic features. To repeat what I have said elsewhere: \"The fungi in their reproduction and inheritance follow exactly the same laws that govern these activities in higher plants and animals.\" I have tried to sho~v that the fungi are not degenerate organisms which are on their way out in a scheme of evolution and so of little economic importance and scientific interest. The fungi, on the contrary, are progressive, ever changing and evolving rapidly in their own wag, so that they are capable of becoming readily adapted to every condition of life. We may rest assured that as green plants and animals disappear one by one from the face of the globe, some of the fungi will always be present to dispose of the last remains.

Mammary carcinoma in the rat with metastasis induced by estrogen.

Abstract: It has been proven without doubt that mammary cancer and other types of cancer can be induced in rats by administration of estrogens. In a series of experiments with 85 rats subjected to various types of estrogenic treatment it was found that a daily dosage of 200 gamma of estrone administered intramuscularly was most suitable for the detailed study of the mechanism of cancer production in the mammary gland after 150-200 days. Injections of smaller doses would produce cancer in 350-400 days; cancer can be obtained more quickly by the implanting crystalline hormone in the form of pellets or with injections of hormone in oil. Attempts have been made to induce mammary carcinoma with estradiol and diethylstilbestrol; results from such experiments are not yet completed.