No. I.] SPERMATOGENESIS OF BATRACHOSEPS. 3 



I. Introductory. 



Owing to a projected and extended voyage, this paper had 

 to be brought to a sudden close, and much which I had in- 

 tended to include in it had to be left out and deferred to a 

 second part. This latter half will include the somatic mitosis 

 of the polymorphous spermatogonia, the evolutions of the 

 spermatids and their development into spermatozoa, and also 

 a discussion of the literature. In this paper I have merely 

 endeavored plainly and briefly to describe my own investiga- 

 tions, and time has hardly permitted me even to touch upon 

 those made by others on the same subject. 



The results of the present investigations, of whatever value 

 they may be, are principally due to improved cytological and 

 optical methods, especially to the new fixatives and to the 

 achromatic light, all described in their proper places. With- 

 out them the chromioles would yet have remained a mystery, 

 at least as far as my own investigations are concerned. The 

 figures illustrating this paper have been corrected as many as 

 four different times, and the first thirty figures made have been 

 completely redrawn, in order to secure that accuracy of detail 

 which can only be had after repeated failures. 



It is proper to state here that the testes of Batrachoseps are 

 very favorable for study, being small and containing large cells. 

 But these advantages are more than offset by the scarcity 

 of the material. While these batrachians are very common 

 almost everywhere in California, their testes are only active at 

 a time when it is almost impossible to procure any specimens 

 of the species. Batrachoseps attenuatus is only adult in the 

 months of June and July, at a time when, on account of the 

 dry season, these animals have retired down in the ground, 

 almost out of reach. In the summer of 1897 I had, however, 

 the good fortune to find in the end of June three fully adult 

 specimens at Monterey, Cal., in a damp meadow which had 

 been kept cool by the fogs from the ocean and shaded by 

 overhanging trees. The largest of the three specimens was 

 made useless by an accident in sectioning the testes; the 

 others, however, turned out most admirable preparations, 



