246 KIY03HI MASUI. 



thronglaout the growth stage and the rechictiou division. The liehavior of tULs 

 chromosome is entirely similar to that of the horse. 



9. The Ijehavior and form of the mitochondria arc entii'clr similar to 

 those of the mouse. 



10. The chi'omatoifl body appears in the early prophase. This body can 

 be seen in the reduction division, but usualh- disappears in the secoml-uy 

 spermatocyte. 



11. Tlie behavior of the centrosome and of the idiozome in tlie formation 

 of the spermatozoa, except in some points, is entirely similar to that of the 

 guinea-pig, i«ix)rlod by IMeves ('99) 



in. Conclusion. 



1. Fi'om the results obtained l)y the measm'ement of the size of the 

 spermatogonia! chromosomes, it is found that pairs of chromosomes exist and 

 that there is a constant relation betvreen their size and theh" form. In the 

 series of chromosomes arranged according to the size and form, tno sj^xjcial 

 chromosomes can be seen which are probably the sex-chromosomes. 



2. The variation in the number of chromosomes in the rabbit is probably 

 due to the fragmentation of certain chromosomes caused liy the fixation of the 

 materials. 



3. The syuisesis is the normal process which occurs in the definite period 

 of the siDcrmatocj-te. 



4. The conjugation of the chromosomes probably takes place by 

 te'osynapsis in the mouse and parasynapsis in the ral)bit. 



5. IVom the liehavior of the sex-chromosomes it is conceivable that vdth 

 i-egards to the existence of the sex-chromosomes, dimorphism must exist among 

 the spermatozoa. 



6. The nucleolus of the six>rmatocyte does not ivprcsent accumulations 

 of by-products of the nuclear actions Init consists of the gi-ound subsfaiuce 

 (plastin ?) aud the other achi'omatic substance which is x)rol>ably to be used 

 in the gi'owth of the chromatin spiremes. 



7. The change of staining capacity of the chv.imatin spiremes in the 

 growth period is due to the accumulation of the achi"omatic substance in the 

 chromatin epircmes. 



