Spermatogenesis in spiders. 517 



found on the edge of the spindle (Fig. 4 A), divide and are well up 

 to the two poles of the cell before the autosomes separate (Fig. 5 A). 

 As these two chromosomes go to the poles of the spindle, they may 

 appear to be of différent forms. Sometimes the rods are more or 

 less twisted about each other ; this is perhaps the form more usually 

 met with. At other times the rods are bent into U-shaped bodies 

 and these cross in such a way that all the ends point in the same 

 direction. Here we get the impression that the accessory body is 

 made up of four elements. At other times the two elements may 

 lag behind one onother. The first two types are shown in Fig. 5. 

 Whatever the appearance of these bodies, however, the essential 

 point is that the accessory chromosome is made up of two rods and 

 these arise through the division of two spermatogonial chromosomes. 

 The elements of the accessory chromosomes come to lie well up to 

 the poles before the autosomes go apart. Occasionally, however, 

 the autosomes seem to divide as early as the accessory elements 

 and in such cases the latter appear to lag behind (Fig. 10). 



During the metaphase of the last spermatogonial division no 

 trace of the ctetosomes has been found. 



Autosomes. 



Metaphase. The division of the autosomes is not attended 

 by any striking behavior, though very occasionally one of these 

 bodies will divide earlier than the rest. 



Telophase. The course of the accessory chromosomes and 

 the autosomes during the early stages of the division has been 

 described. As the chromosomes draw apart to the poles of the cell, 

 the accessory elements are more or less conspicuous because of 

 their form and their position (Figs. 6, 8, 10 A). The autosomes 

 appear as simple rod-like elements. 



('tetosomes. 



The telophase of the last spermatogonial division is of extreme 

 interest because we have here the first hint of the way in which 

 the ctetosomes will behave during the following divisions. As the 

 autosomes draw apart, we find lying in the mantle fibers of the 

 spindle, a rather small chromatin body (Fig. 6). The appearance of 

 this body is typical as shown in the figure but occasionally we get 

 a side view which shows the make up of the mass (Fig. 7). Here 



