45 6 MARIE A. HINRICHS. 



Such experiments have been made with (a) Fundulus and 

 ultraviolet radiation, Hinrichs, '25, (b) Arbacia and ultra- 

 violet radiation, Child, '24, footnote, p. 109, Hinrichs, '26, 

 and (c) Arbacia and visible radiation following sensitization with 

 eosin, neutral red, benzoflavine, and methylene blue, Hinrichs, 

 '26. So far, experiments with radiation have given results 

 entirely parallel with those produced by chemical and other 

 physical agents, thereby further confirming the view of the non- 

 specific and quantitative nature of susceptibility relations along 

 the body axis. 



In previous experiments it w r as found that the larval develop- 

 ment of Arbacia may be modified by subjecting the fertilized egg, 

 preferably during the first few minutes after insemination, to 

 doses of radiation which, although not immediately lethal, may 

 produce sufficient injury to interfere with the normal succession of 

 developmental processes. In further experiments with Arbacia, 

 the same types of differential modification were produced by 

 subjecting either component of the zygote, before fertilization, 

 to the proper dosage of radiation. 



Much experimental work has been reported in which chemical 

 treatment of either or both sex cells before insemination has 

 brought about abnormal development. Stockard, in a series 

 of papers, reports the production of abnormalities through 

 the mating of alcoholized guinea pigs. (See Stockard and 

 Papanicolaou, '18, for references to previous papers.) Rondeau 

 and Luzeau, '01, with isotonic NaCl and sugar solutions on the 

 eggs of Rana fusca, Gee, '16, with alcohol and NaOH on the 

 germ cells of Fundulus, and Dungay, '13, with distilled water, 

 chemicals, heat and cold, on Nereis and Arbacia sperm, were in 

 each case able to produce modification of larval development; 

 and the latter author recorded distinct differential effects. 

 Bohn and Drzewina, '23, were able to diminish motility in the 

 sperm of Strongylocentrotus by the combined action of neutral 

 red and light, and also by the use of KCN, KC1, and of distilled 

 water (Drzewina and Bohn, '12, '23, a, b). O. Hertwig, '13, 

 using chloral hydrate and strychnine nitrate on the sperm of 

 Rana fusca, was able to produce spina bifida, and a general delay 

 of organ-formation and hatching. He points out the similarity 



