. Biological effects of radiation; mechanism and measurement of radiation, applications in biology, photochemical reactions, effects of radiant energy on organisms and organic products. Radiation; Biology. 1282 BIOLOGICAL EFFECTS OF RADIATION may, as indicated, be directly induced or may arise as a result of gene mutation (asynapsis) or as a by-product of chromosomal reorganization, while monosomy and polysomy may themselves give triploidy. The dotted lines indicate that polyploidy and extreme nuclear disruption may possibly be secondary products of induced gene mutation. Thus, Stein (456, 466
. Biological effects of radiation; mechanism and measurement of radiation, applications in biology, photochemical reactions, effects of radiant energy on organisms and organic products. Radiation; Biology. 1282 BIOLOGICAL EFFECTS OF RADIATION may, as indicated, be directly induced or may arise as a result of gene mutation (asynapsis) or as a by-product of chromosomal reorganization, while monosomy and polysomy may themselves give triploidy. The dotted lines indicate that polyploidy and extreme nuclear disruption may possibly be secondary products of induced gene mutation. Thus, Stein (456, 466, 47) interprets her "phytocarcinome complex," which is characterized by these effects, as due to an induced mutation. Chro- mosomal reorganizations are indicated as the direct consequences of irradiation and may give rise in subsequent generations to haploidy, triploidy, and tetraploidy. In addition they are shown as a mode of origin of gene mutations, a significant type of effect from the point of view of the origin of mutation. In this connection the results of Stubbe (48) are significant. Using mature pollen of Antirrhinum majus, he compared mutation frequency after treatment with grenz (supersoft) rays and longer and shorter X-rays, the dosage in each case increasing in geometrical progression. That the curves obtained from the three treatments are directly comparable is interesting in other connections, but their present significance lies in their consistent and decided fall from a rapidly attained peak, followed by their rise. As to the nature of the mutations themselves, those responsible for the initial rise in the curve were similar or equivalent to those which had been observed in Antirrhinum under natural conditions. Stubbe's results may be interpreted as indicating that a series of qualitative (intragenic, chemical) changes were initially induced, followed by quantitative (extragenic, chromosomal) alterations productive of lethality and giving by-products
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