372 RUTH J. STOCKING. 



between these two stages such intermediate conditions as Dr. 

 Wilson found in Lygceus and Oncopeltus ('12). The presence of 

 such stages would probably change the interpretation I have put 

 upon the stages described. I was unable, however, to find any 

 such intermediate conditions, and so have been forced to hold to 

 the present interpretation. 



These contraction stages were very common in my material, 

 but the section figured, which I have interpreted as a cross 

 section of such a clump, is a rather rare occurrence. This is to 

 be expected, since sections through many different planes would 

 give a side view of a mass crowded at one side of a cell, while a 

 section through one plane only would give such a polar view as is 

 shown in Fig. 3. 



I have interpreted this contraction phase as the stage at which 

 conjugation takes place, thus placing synapsis much earlier in 

 the process of spermatogenesis than Miss Stevens had done in 

 her earlier work. According to this interpretation, in Fig. 3, 

 chromosomes a and b, c and d, e and /, g and h, x and y, are cross 

 sections of pairs of chromosomes not yet united; chromosomes 

 j and k, I and m, o and p, are side views of such pairs; and q and r 

 are the tops of the thickened loops formed by two joined chromo- 

 somes. 



Miss Stevens followed the work up to this point, and it was 

 under her direction that this stage came to be interpreted as the 

 conjugation stage. It was her opinion that the type here was 

 telosynaptic. 



As the side view of this stage shows only a very dense, irregular 

 chromatin mass, and the cross sections of this stage are so rare, 

 the actual meeting of the two chromosomes would be very difficult 

 to see; I did not succeed in finding it. But the fact that at the 

 end of this stage never more than ten chromosomes can be found 

 in a cell, while just before it (that is, in the last spermatogonial 

 telophase) twenty were present, is in itself proof that conjugation 

 takes place at this time. And the appearance of the short loops 

 (Figs. 4, 5, 6, 7, 8) as the condensation stage opens up, is an 

 indication of the manner in which synapsis has occurred. 



The next stage in the observed process is the transformation of 

 these short thick loops into long loops, partly linin, partly chro- 



