THE SPERMATOGENESIS OF DOMESTIC MAMMALS. 373 
9. The resting stage of the secondary spermatocytes can rarely be 
observed, which makes it probable that this stage is of very brief duration. 
10. The second pairing of the chromosomes in the second division was 
not observed. 
11. The second division is equal and homotypic. The accessory chromo- 
some divides like the ordinary ones. 
12. The behavior of the centrosome in the development of the sper- 
matozoa is almost similar to the condition found by MEVES in man. 
13. The chromatoid corpuscle makes its appearance during the growth 
stage. In the final development of the spermatozoa it is probably cast off, out 
of the body of the spermatozoa. 
14. The mitochondria make their appearance during the postsynaptic 
stage. In the spermatids most of them give rise to a mass which is similar 
to the “ Nebenkern” in the insects, while the main portion finally comes to 
occupy the middle part of the spermatozoon. 
