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SCIENCE 



[N. S. Vol. XLII. No. 1079 



important from his interpretation which 

 have been obtained as the results of the 

 investigations in his laboratory. The fol- 

 lowing facts are emphasized by him: 



1. Fertilized Ascains eggs, which had 

 been radiated several hours showed patho- 

 logical nuclear division figures in which the 

 chromatin bodies are represented by irreg- 

 ular masses of chromatin granules. They 

 divide slowly and begin at last to degen- 

 erate by caryolysis. (Paul Hertwig.) 



2. By intensive radiation of several hours' 

 duration, sperm threads of the sea-urchin 

 are so affected that, while they are able to 

 fertilize the egg and to stimulate the egg 

 nucleus into spindle formation, they lose 

 their ability to form normal chromosomes 

 and thus are eliminated from development 

 partially or completely, sooner or later, 

 depending on the degree of the injury. 

 (G-linther Hertwig.) 



3. An elimination of the sperm nucleus 

 which is derived from intensively radiated 

 sperm threads has been observed during the 

 first and second divisions in eggs of the 

 frog (Paula Hertwig) and of the trout 

 (Oppermann). 



4. For the elimination from the develop- 

 ment process of the radiated sperm chro- 

 matin which has lost its capacity to develop, 

 the fact established beyond doubt for the 

 radiated larvte of Triton speaks convinc- 

 ingly, that the somatic nuclei have only half, 

 or the reduced, number of chromosomes. 

 Since the male chromosome complex fails 

 to take its part in the development, due to 

 the radiation, the somatic nuclei have only 

 the female complex. (Oskar Hertwig.) 



5. This fact agrees with the result ob- 

 tained for frog, toad, Triton and trout 

 embryos, that after the maximum radiation 

 of the sperm which are to be used for fertili- 

 zation, the nuclei of the different cells are 

 strikingly smaller than are those of the con- 

 trols of the same age, and both their sur- 



faces and their volumes are in ratio to 

 those of the control as 1:2. For the con- 

 elusion, that the chromosome number of the 

 nucleus is the haploid, may be drawn from 

 the fact established by numerous experi- 

 ments that the volumes are reduced almost 

 to half. (Oskar Hertwig, Giinther Hert- 

 wig, Oppermann.) 



6. The results obtained from cytological 

 investigation offer the possibility of explain- 

 ing a fact highly remarkable from a physio- 

 logical standpoint and at first glance a very 

 puzzling one, that eggs, which would ordi- 

 narily fail to develop from the germinal 

 vesicle stage when fertilized by foreign 

 sperm because of the union between dis- 

 harmonious idioplasms, are spared from de- 

 struction and may develop into larvce if 

 only the sperm from the different species are 

 radiated intensively before fertilization. 

 The puzzle is solved by the simple reflection 

 that the effect of the union of the dishar- 

 monious idioplasms with its disastrous con- 

 sequences is avoided by the injury to the 

 radiated chromatin, although the sperm 

 thread penetrates into the egg and stimu- 

 lates development. Although the radiation 

 of the strange sperm has been destructive 

 to the sperm, it has been favorable to the 

 fertilized egg, just as in the living body a 

 poison substance is counteracted by an- 

 other poison. 



The investigation of radiation effects on 

 Ascaris eggs was imdertaken by Fraiilein 

 Paula Hertwig in order to obtain definite 

 evidence on the facts at the basis of the 

 biological hypothesis. Her conclusion is 

 that the division of the eggs is retarded, 

 and pathological appearances are very soon 

 noticeable after the radiation ; chromatin is 

 strongly affected, as already stated, al- 

 though the centrosomes, spindles and other 

 cell organs show no injury; unfavorable 

 action of the cytoplasm is not to be assumed 

 since no change can be seen. She is able to 



