342 ORILLA STOTLER WERNER. 



There is a distinct drop in size between the sixth and the seventh 

 largest tetrads (Nos. 33 and 32). The same size distinction may 

 be noted between numbers 33 and 32 of the soma cells. There 

 is a similar distinction between the 35's and the 34*3 in the 

 spermatocyte and somatic series. The size relations among the 

 shorter spermatocyte rods (Nos. 32-24) and the bivalents de- 

 rived from the globe-shaped chromosomes are apparently about 

 the same as in the soma cells. In each case they form a similarly 

 graduated series. 



In addition to the resemblance in size between the spermato- 

 cytic and the somatic series there is also a striking similarity in 

 form. Tetrad number 38, the largest in the group (Fig. 24), 

 shows that it has arisen from a pair of J's similar to those seen at 

 38Z in Fig. 43, Plate 8. In Fig. 25 the long arms of the J have 

 not yet disjoined ; the shorter arms have. This chromosome is 

 well shown in Fig. 52 where the disjoining is almost complete. 

 Chromosomes 36 and 35 also show that they have arisen from a 

 pair of J's (Fig. 25). In each of these chromosomes the long arms 

 of the J's have not disjoined while the shorter ones have. Chro- 

 mosome number 37 (Figs. 24, 25, 26, 27, also Plate 9) shows 

 constrictions similar to those found in number 37 in the soma 

 cells, although these are more apparent in the tetrads, i.e., the 

 constrictions are deeper. In some of these cases only one of the 

 constrictions is apparent but whether one or both are present, 

 when they do appear, each seems to be in about the same posi- 

 tion in the members making up the tetrad that it would occupy in 

 the somatic homologues. 



GONOMERIC GROUPING. 



The probable existence of an odd chromosome in one of the 

 gametes, as well as a definite number of the large chromosomes in 

 each of the gametes, is further evinced in somatic cells in the 

 grouping of the chromosomes in early metaphase. I have ex- 

 amined numerous cells in metaphase in both sexes. In the cells 

 of the male the large chromosomes are grouped six on one side of 

 the forming equatorial plate and six on the other (Figs. 3, 5, 6). 

 In the cells of the female there are six on one side of the plate and 

 seven on the other (Figs. 17, 18, 19, 20, 21, 22). In every case 



