604 



appreciation. Nevertlieless, he has added few material facts that are 

 essentially new. On the other hand, in my paper, I traced the history 

 of the sex-cells through to adult life and considered the seasonal changes 

 in the sex-cells of the male, while Dustin has studied no stages later 

 than that of 8,95 mm. This is to be regretted, since it has not afforded 

 him a sufficient basis for his claim, that later generations of sex - cells 

 arise by differentiation from the peritoneal cells. 



Dustin's determination to repeat my work would seem to indicate 

 that he expected to find conditions essentially different from those that 

 I had reported. His contempt for my paper may be judged by the 

 following extract from his earlier paper "Recherches sur I'origine des 

 Gonocytes chez les Amphibiens", Arch, de Biol., T. 23, p. 504 — 505 : 



„Signalons toutefois le travail de B. M. Allen (2 — 3) sur Chrysemys margi- 

 nata. Pour cet auteur, les cellules sexuelles apparaitraient chez les embryons trfes 

 jeunes, dans I'hypoblaste, au point de reunion de I'aire opaque et de Faire trans- 

 parente. Dans la suite du developpement, ces cellules ^migreraient vers la racine 

 du m^sentfere, s'y localiseraient un certain temps, puis se porteraient definitivement 

 vers Föpithelium germinatif. Nous estimons, toutefois, qu'on pourrait faire ä ce 

 travail la critique que fit MiNOT (58) aux partisans du gonotome, c'est-a-dire que 

 les cellules sexuelles hypoblastiques ne seraient que des cellules en mitose." 



The event has shown that Dr. Dustin was quite unable to pick 

 flaws in the main features of my account, his recent paper serving as 

 a most satisfactory confirmation of my main contention, that the early 

 sex-cells of Chrysemys arise in the entoderm near the junction of the 

 area pellucida with the area opaca and that they migrate from this 

 region to the median line and finally pass dorsally up through the 

 mesentery as it is developing, to later migrate to their definitive po- 

 sitions in the sex-gland anlagen on each side of it. Dustin lays much 

 stress upon different terms which he applies to certain points in this 

 migration path, as follows : a. glandes paires primaires. b. glande im- 

 paire mediane, c. glandes paires secondaires ou definitives. If this 

 affords him satisfaction, I willingly grant him the pleasure of thus ap- 

 plying names to certain points in the path that I had previously traced 

 out. He criticises me for not recognizing these "laws" as he terms 

 them. I can not feel that we are justified in attaching a general phylo- 

 genetic significance to this path of the sex - cells. A comparison of 

 different types of vertebrates does not show much uniformity in this 

 regard. 



As a result of my own work upon Necturus "The Origin of the 

 Sex-Cells in Necturus", Science, N. S. Vol. 33, 1911, p. 268, I am con- 

 vinced that the sex-cells there arise from the inner edges of the lateral 

 plates of mesoderm, as Dustin found in Triton ('07). In the anurans, 

 on the other hand, they are first noted in the entoderm in the median 

 portion of the roof of the archenteron, as first shown by my work on 

 Rana pipiens Allen ('07), and later substantiated by King ('08) in 

 Bufo lentiginosus , and by Kuschakewitsch ('10) in R. esculenta, 

 Dustin ('07) to the contrary, nothwithstanding. This paper of Dustin's 

 is discussed in some detail in a recent paper of mine upon the oi'igin 

 of the sex-cells in Amia and Lepidosteus, Journal of Morphology, Vol. 22, 

 1911. Whether this distinction is general or not, it serves to show the 



