82 bulletin: museum of comparative zoology. 



greater or less degree. The tendency for adjacent granules to fuse 

 probably accounts for some of the variations to be noticed. If one 

 will compare in order the examples I, m, a, and c, (fig. 98) the different 

 steps in the fusion of granule no. 4 with the smaller, yet prominent, 

 granule close to it will be seen. As the threads shorten during the 

 later pachytene and postspireme stages, this coalescence of adjacent 

 granules becomes more noticeable and the individual granules all 

 finally lose their visible identity in the compact metaphase chromo- 

 somes. 



It will be observed that the members of a pair of granules may also 

 appear to be fused together into a single ma|SS. An example of this is 

 seen in figure 98, n, granules 4 and 5. This fusion must be very 

 temporary in character, since it is not the general rule, and since the 

 granules separate again in the postspireme stages, as shown in figure 

 63 (Plate 6) ; yet so close an association of these granules apparently 

 offers opportunity for the exchange of chemical substances between 

 them. In the case of the proximal granules (no. 1), the members may 

 not only fuse with each other but, as previously noted, characteristi- 

 cally unite with the polar granules of other chromosome-pairs to form 

 the composite granules. The association is fully as close as in that of 

 any single pair, for frequently all traces of the outline of individual 

 granules is entirely lost, as, for example, in figure 34 (Plate 3). Al- 

 though the individual granviles separate out again in the postspireme 

 stages, if we admit that there is an exchange of chemical substances 

 between members of a single pair of granules, I think we must also 

 assume it for the polar granules of the different chromosome-pairs. 



At j (fig. 98, Plate 8) may be seen another example of an expanded 

 polar granule, such as has already been mentioned. The possible 

 significance of this peculiarity will be discussed on page 112. 



It will be instructive to compare the members of particular pairs 

 of granules. Figure 58 (Plate 5), as already mentioned, represents a 

 zygotene stage. The paired chromatic threads near the middle have 

 jiist begun to conjugate, while in the case of chromosome-pair B, in 

 the left half of the figure, the two conjugating threads have only 

 recently come to lie side-by-side, for the members of the different pairs 

 of granules are yet distinct. This condition fortunately gives us an 

 opportunity to compare the relative sizes of the members of each pair. 

 On examination it will be seen that the members of the pair numbered 

 4 are not equal in size. This is also true for the pair numbered 3. In 

 the case of number 4, the disparity in size between the two granules 

 is considerable, and it is interesting to observe that this difference in 



