158 Hyhrids between Pheasant and Fowl 



The division stages of the primary spermatocytes, when seen from 

 the side, do not present any features of interest, except that one of 

 the chromosomes is often sharply differentiated from the rest (Fig. 8) 

 I have not been able to find any trace of a lagging element, though many 

 division stages have been carefully examined. 



Secondary Spermatocytes. These cells are usually a little smaller 

 than are those of the primary spermatocytes. There is, however, at this 

 stage, a great tendency for the chromosomes to undergo secondary fusion, 

 which is in many cases in pairs. As a result of this, in the majority of 

 cells, five or six clumps of chromatin are seen (Fig. 9). This fusion in 

 pairs, however, is by no means a regular occurrence as the number of 

 chromatin masses in the secondary spermatocytes varies from 1 to 7 or 8 

 (Fig. 10). I have not observed a secondary spermatocyte with more than 

 eight chromatin elements so that it appears as though a certain amount 

 of pairing always tak^s place. 



This phenomenon is not of rare occurrence and has been recorded in 

 the spermatogenesis of insects and mammals. The spermatids and sper- 

 matozoa are of the normal type and do not require any special description. 



Spermatogenesis of Gold Campine Cock. 



The phases in the development of the spermatozoa are very like those 

 described for the male pheasant. Guyer has recently published the 

 results of research on the spermatogenesis of the fowl and arrives at the 

 following conclusions : 



1. The somatic chromosome number is 18 of which two are sex 

 chromosomes. 



2. During synapsis pairing of the chromosomes takes place so that 

 nine bivalent chromosomes appear in the primary spermatocytes. The 

 two sex chromosomes pair together, but during the division of the cell 

 they behave as a single bivalent, so that two kinds of spermatocytes are 

 formed, one with 8 + 2X chromosomes, the other with 8 chromosomes. 



3. Secondary fusion occurs in the secondary spermatocytes so that 

 the majority of the cells contain four or five clumps of chromatin. 



4. Spermatocytes with four chromatin masses frequently show 

 abnormal characters, which leads to the conclusion that only one class 

 of spermatid, that with the X chromosomes, develops into functional 

 spermatozoa. 



