94 bulletin: museum of comparative zoology. 



trace the pair through all the stages from the spermatogonia to the 

 spermatids, thus constituting a demonstration of a case of continuous 

 identity, or individuality, through these stages. It was also possible 

 to recognize chromosome-pairs B and C in the spermatogonial telo- 

 phases as well as in the second spermatocytes and spermatids. 



8. In the earlier pachytene stages, chromosome-pair B was found 

 to have a definite arrangement of granules or chromomeres, and it was 

 shown that the relative sizes and positions of these chromomeres re- 

 mained constant for similar stages, not only in different cells of a 

 single individual, but also in all the thirteen animals. 



9. The spermatogonial divisions showed that each chromosome 

 forms a sac or vesicle in the earlier telophases, and that it expands 

 and becomes diffused within these vesicles; that, although the vesicles 

 appear to coalesce, there is always a remnant of each chromosome 

 visible in the center of the region occupied by the vesicle, and that in 

 the prophase the chromatin concentrates about this remnant or core 

 and there forms a spirally coiled thread, which develops into a prophase 

 chromosome. 



10. Study of somatic cells showed:— (1) that chromosome B 

 could be recognized in the connective-tissue cells within the follicle, 

 and (2) that cells of the follicular envelope, which are probably in a 

 state of senescence, still preserved the normal number (23) of chromatic 

 masses. 



11. The polar granules are constant features of the organization 

 of the individual chromosomes, as was shown by Pinney ('08); but 

 in some cases (chromosome-pairs A and B) they may become modified 

 to give rise to expansions which resemble the "vesicles" described by 

 Carothers ('13), as well as the "plasmosomes" of most authors. The 

 polar granules tend to unite into composite granules at all of the diffuse 

 stages of chromatic evolution. 



12. The accessory chromosome behaves in the manner that is 

 typical for the Acrididae. It forms a large separate sac or vesicle in 

 the earlier spermatogonial generations and a peripheral compact mass 

 in the telophase of the last spermatogonial division. During the 

 leptotene and zygotene stages it may unravel into a long loop, which 

 in some cases is equal in length to a great circle of the nucleus. In the 

 pachytene stages it reassumes a compact form, but may b 5 attached 

 by its polar granule to the polar granules of other cln-omosomes and 

 thus become attached to a composite granule. It passes to one pole 

 undivided in the first maturation division but divides in the second. 



