No. 526] SHORTER ARTICLES AND DISCUSSIONS 627 



Aside from this study, and that of Guyer spoken of above, 

 I know of no examination which has been made of the gonads of 

 hybrid vertebrated animals. The conditions which T have found 

 in canaries resemble closely those found by Guyer. in pigeons. 

 The observations of Ancel and Bouin 3 on cryptorchid horses 

 resemble to quite an extent, those by Jordan upon the mule 



Hybridization experiments with lower forms of animals throw 

 some light upon the behavior of the germ cells concerned in 

 fertilization. Moenkhaus found that he could cross Fundulus 

 and Menidia, two species of fishes, and obtain normal hybrids. 

 Owing to the differences in size of the chromosomes in the two 



of the egg and uf those of the spermatozoon ;md it was possible 

 to follow them through the embryonic history, through the vari- 

 ous mitoses of segmentation and later. Here, the chromosomes 

 were in no way antagonistic and proeeeded through the mitoses 

 side by side. 



Balzer 5 performed a series of very interesting experiments 

 upon several species of eehinoderms occurring in the Bav of 

 Naples. He used four species, Strongyloccntrotus, Echinus, 

 Arbacia and Splia ra-li i ,ms. making reciprocal crosses. Crosses 

 between Strongylocc >tl rot its. Echinus and Arbacia gave normal 

 fertilizations, with no loss of chromatin in the earlier segmenta- 

 tion anaphases, and the plutei exhibited normal skeletons, except 



