SEX-CELLS OF AMIA AND LEPIDOSTEUS 33 
les Reptiles,’ (Archives, de Biologie, 1910). This article deals 
with the origin of the sex-cells in Chrysemys marginata, the form 
which served as a subject for my own work of 1906. As noted 
above, Dustin in his paper ‘‘Recherches sur l’origine des gono- 
eytes chez les Amphibiens”’ 1907, exhibited scant respect for my 
work on the sex-cells of Chrysemys. It was, no doubt, in large 
part, this feeling that prompted him to repeat my work. While 
he, no doubt, expected to find in this form a confirmation of his 
previously expressed views, he is led to substantiate completely 
my statements regarding the entodermal origin of the sex-cells. 
He traces them along the same migration path that I demon- 
strated four years before. For all this he now gives me full credit 
and support; but takes issue with my statements regarding the 
distribution of the sex-cells prior to their migration into the em- 
bryo, and, furthermore, claims to have-evidence to show that 
there is a new formation of sex-cells, due to a transformation of 
ordinary peritoneal cells. These points of controversy and 
certain other minor ones can not be considered here, but I promise 
a full discussion of them in another place. I may say that I am 
fully prepared to maintain my views upon all of the points at 
issue. 
On my part, the work that I have carried on upon Necturus 
since this paper was written, has given me results quite similar 
to those at which Dustin arrived in his work upon Triton. I 
may say that preliminary studies have convinced me that the 
sex-cells arise in an essentially similar manner in Amblystoma. 
We then see that, in all three of these urodeles, the sex-cells 
arise from the inner edges of the lateral plates of mesoderm. I 
owe it to myself to call attention to the fact that I have at no 
time disputed the accuracy of Dustin’s work upon Triton. While 
the evidence seems to me quite clear that this is the usual, if 
not the universal, mode of origin of the sex-cells among the uro- 
dele amphibians, I am ready to maintain with equal vigor the 
entodermal origin of the sex-cells in the aruran amphibians, 
at the same time admitting the possibility that exceptions to 
this apparent rule may be discovered. I do not feel however, 
that Dustin has proved his case in Rana fusca and Bufo vul- 
