138 T. H. MONTGOMERY, JR. 



somes ; and hence that the first maturation mitosis separates 

 paternal from maternal chromosomes. 



The third and fourth of these conclusions were new ; the 

 second has been a matter of much controversy, while the first 

 has a considerable number of cytologists in its support. If 

 these results can be generally established they will give a co- 

 herent basis for understanding the part played by the chromo- 

 somes in heredity, taken in conjunction with the important con- 

 clusion of Van Beneden [ that the male pronucleus has a number 

 of chromosomes equal to that in the female pronucleus ; and of 

 Henking 2 and O. Hertwig 3 that the maturation phenomena cor- 

 respond very closely in the ovogenesis and spermatogenesis of 

 the same species. 



It is not my purpose here to go over the whole controversy 

 and discuss in full the opposing views, for that has been done in 

 my preceding papers, but rather to draw attention to a few of 

 the more important results, and to add some new observations. 



i. THE FIRST MATURATION MITOSIS IN AMPHIBIA. 

 Janssens and Dumez 4 have very recently reexamined the 

 spermatogenesis of Amphibia, particularly with regard to my 

 results on Plcthodon and Desmognathus, and decide that my 

 position is both untenable and unproved : that the heterotypic 

 mitosis is an equational division, and not a separation of entire 

 univalent chromosomes as I had maintained. They state (p. 

 433) : " On est tout etonne de ne trouver dans le texte de Thos. 

 H. Montgomery aucun argument pour cette these." They do 

 not mention my strongest argument at all, namely that the space 

 enclosed by the heterotypic chromosome is a space separating 

 two whole univalent chromosomes, and not a longitudinal split 

 between two halves of a single chromosome, because this space 

 is largest in the earliest stages, and not, as one would expect if it 



1 " Recherches sur la maturation de Foeuf et la fecondation," Arch. Biol., 5, 

 1883. 



2 " Ueber Spermatogenesis und deren Beziehungen zur Eientwicklung bei Pyrrho- 

 coris apterus M.," Zeit. iviss. Zoo/., 51, 1890. 



3 " Vergleich cler Ei- und Samenbildung bei Nematoden," Arch, inikr. Aitat, 

 36, i8qo. 



4 " L' Element nucleinien pendant les cineses de maturation des spermatocytes 

 chez Batrachoseps attenuatus et Pletodon cinereus," La Cellule, 20, 1903. 



