WENRICH: spermatogenesis of PHRYNOTETTIX MAGNUS. 99 



De Saedeleer ('13) finds in Ascaris all the typical stages of the 

 growth-period: — leptotene, zygotene, pachytene, and diplotene; he 

 consequently believes that parasynapsis occurs. 



Among the Crustacea parasynapsis has been found by McClendon 

 and by Kornhauser for Copepoda and by Fasten for Canibarus. 

 McClendon ('10) found parasynapsis in both the oogenesis and the 

 spermatogenesis of Pandarus sinuatus, but could not decide which of 

 the maturation divisions were reductional. Kornhauser ('15) gives 

 a very full account of a careful study of the process of parasynapsis in 

 Hersilia apodiformis, thus confirming the earlier results, as to the 

 existence of parasynapsis in Copepoda, of Lerat ('05), Matschek ('09), 

 and McClendon ('10). In this paper he clears up the uncertainty in 

 regard to this group brought about by the unique theories held by 

 Hacker ('92) and his followers. Kornhauser demonstrates very 

 clearly that the so-called ' Querkerbe,' which Hacker and his followers 

 interpreted as the point of end-to-end union, is nothing more than the 

 synaptic point of the chromosomes which have a median or non- 

 terminal spindle-fiber attachment. The Copepoda are thus brought 

 into line with the majority of other forms. Fasten ('14) finds para- 

 synapsis in Cambarus, and although he is dealing with a very large 

 number of clu-omosomes (the diploid number is about 200), his figures 

 of the leptotene and zygotene stages are quite convincing. 



With respect to work on insect material, I have already mentioned 

 that on Orthoptera. The results of Stevens are unusual in that she 

 has described telosynapsis for Blatta ('05), Stenopalmatus ('05), and 

 Forficula ('10b), while in Ceuthophilus ('12a) she found parasynapsis. 

 In the last mentioned article she says (p. 227) " I should not be sur- 

 prised if the range of variation should prove to extend from (a) cases 

 where there is nothing that could be called conjugation, but merely 

 such a pairing without contact even, as will secure segregation of 

 homologous maternal and paternal chromosomes to different daughter 

 cells, through (b) an intermediate condition of telosynapsis and less 

 intimate paras;yTiapsis, to (c) cases where homologous chromosomes 

 are so completely fused in parasynapsis that it is impossible to tell 

 whether the resulting cliromosomes which are segregated in mitosis 

 are identical with those that went into synapsis or not." It may be 

 that more intensive studies will reveal greater uniformity of behavior 

 than Stevens advocated. 



Payne ('14), in a brief description of tetrad formation in Forficula 

 sp., reaches only tentative explanations and conclusions. He finds a 

 variable number of chromosomes in the two maturation divisions and 

 suggests that this might be accounted for b;^- supposing that some of 



