Transmission of Hereditary Characters, 471 



five ") has divided, and before the longitudinal fission of the 

 loops has taken place. The case is also precisely similar, 

 according to Kolliker's own statement, in the segmentation 

 spheres of the Axolotl ; moreover, according to Rabl *, in 

 the epithelial cells of Salamandra the achromatin spindle is 

 distinctly visible, and consequently the centrosomata have in 

 all probability divided, before the occurrence of the cleavage 

 of the chromosomata. 



This at once weakens everything else which is asserted by 

 Kolliker and Weigert with respect to the importance of the 

 nuclei for the growth and metabolism of cells. Probably no 

 one will nowadays deny that the nucleus is of eminent 

 importance for the processes of growth, assimilation, and 

 secretion in cells. This, however, proves nothing whatever 

 with regard to the question whether the nucleus is the sole 

 agent in heredity. And with regard to the circumstances 

 which have been rendered applicable by Strasburger from 

 the botanical side, I think that I may here leave these out 

 of consideration, because until recently hardly any attention 

 has been paid to the centrosomata and their role in the cells 

 of plants. It was not until the present year that the fact that 

 they are of general occurrence here also was maintained by 

 Guignard f. 



We now come to the argument, which nowadays probably 

 ranks as the most important of all, as the actual experimental 

 basis of the theory, in consequence of which even so inde- 

 pendent and far-sighted an investigator as Biitschli found 

 himself compelled to alter his views. This is the attempt of 

 Boveri, of which mention has already several times been 

 made, to produce an organism devoid of maternal characters. 

 Boveri found that, in Echinids, fragments of ova devoid of 

 nuclei (obtained by shaking) are capable of being fertilized 

 and developing into larvse. tie further makes use of the 

 experience obtained by O. and R. Hertwig as to hybridization 

 in these animals : on fertilizing the ova of one species (A) 

 with the spermatic fluid of another (B), larvse are formed 

 which are intermediate in character between the typical larva3 

 of A and B. Boveri now fertilized an egg-fragment of A, 

 from which the nucleus had been eliminated by the process 

 of shaking, with sperm from B, and it was found that a 

 larva developed which entirely possessed the characters of the 



* C. Rabl. "Ueber Zellthcilung," Morphol. Jahvbiioher, 10 Bd. (1884). 



t (Juigiiard, ' Comptes liendiis,' Marcli 9, 18'Jl. I became acquainted 

 witli this paper tbrougb a statement by van Tiegliem in the * Jom-nal de 

 Botanique,' 5 aimee, no. 7, p. 101 ; for the reference to this I am indebted 

 to my friend Dr. Kolderup-Rosenvinge. 



