412 Sidney I. Kornhauser 



cliided in an opfical section. For instance, from the positive pole, take 

 an optical section passing tlirough the middle of such a cell as Figure 15 

 represents. The conjugant (cg.) would be seen three times: a length 

 of double thread and two cross sections of the non-conjugated portions. 

 Between thirty and forty cross sections (average thirty-five) of double 

 and Single threads could be counted in ceUs showing conjugation (Fig. 16), 

 a result intermediate between that of the leptotene bouquet and that of 

 the zygotene bouquet. 



As has already been stated, it is either just previous to or dimng the 

 conjugation stages that the fusion of the two nucleoli takes place and 

 the Union of the cyto-plasmosomes forms the "nuclear cap". We 

 immediately ask ourselves: Are these unions merely coincident with the 

 conjugation of the chromosomes, or are these plasmatic bodies acted 

 upon by the same force or forces which cause the chromosomes to con- 

 jugate? An answer to these questions cannot be given, for we know 

 too little about the forces causing conjugation; but these forces are to 

 be sought, I believe, rather in the chromosomes themselves than in the 

 centriole, which probably does bring about the orientation of the loops 

 in the bouquet stage. My reason for beUeving that the conjugating force 

 is resident within the chromosomes themselves, is based on the fact that, 

 dm-ing the transitional or conjugation stage, the regulär polar arrangement 

 is partly lost in the approximation or search (?) of homologous chromo- 

 somes for each other. The conjugating force, during this period, shows it- 

 self stronger than the orienting force. 



The region of the testis immediately following the conjugation 

 stage (farther cephalad) is composed entirely of cells in the zygotene 

 bouquet stage (Fig. 1, Plate IV: Figs. 12 (/, 17, Plate V). Throughout 

 this period the chromatin bands show a light longitudinal line with the 

 deeply staining chromioles symmetrically arranged along both sides. 

 There is no indication of an actual fusion of the conjugants in Hersilia. 

 The "nuclear cap" and nucleolus are very prominent in the bouquet 

 stage; but in the older cells, that is, in those nearer the maturation zone, 

 the nucleolus decreases in size and the "nuclear cap" loses to a great 

 extent its affinity for Heidenhain's haematoxjdin. 



The end of the bouquet stage is marked by the loss of the polar 

 orientation of the chromatin bands, which, instead of remaining loops, 

 often show a sharp angle either at or near the middle of theii- length. 

 Soon the conjugants begin to separate from each other along the light 

 longitudinal line. This process is illustrated in Figures 19—21 (Plate V); 

 it may begin at one or both ends of a pair, in which cases it opens out 



