78 ' H. B. GOODRICH 



ever, as among plants, (Cardiff '06, Rosenberg '09, Miyake 

 '05, etc.) and in Hydrophilus (Arnold '08) these bodies are 

 conspicuously paired. That the pairing is significant, based 

 on some relation between the thread and not an optical illusion 

 as has been suggested, is shown by the fact that granules lie 

 opposite one another on the parallel threads and that opposed 

 granules are of the same size. It is unfortunately impossible 

 to make accurate counts of these bodies but they in no way 

 approach 70, the number to be expected did they represent 

 a precocious splitting of the chromosomes of the last gonial 

 telophase, but rather they approximate the diploid number and 

 therefore more probably represent the pairing of chromosomes 

 preparatory to synapsis. In this case it is clear that in Ascaris 

 incurva, the evidence favors parasynapsis as a haploid number 

 of chromatin bodies arranged in pairs transform into parallel 

 threads and after synizesis in spermatogenesis the pachytene 

 threads show a longitudinal duality. 



It has been noted that there exists a difference in the nature 

 of the pachytene threads in spermatogenesis and oogenesis. 

 In the former the pachytene threads are often conspicuously 

 double, in the latter such a structure is not clear; therefore there 

 may be a more intimate union of threads in oogenesis than in 

 spermatogenesis. Unfortunately httle work has been done 

 on the comparative study of oogenesis and spermatogenesis 

 in the same forms by the same workers. Stevens ('03, '05, '10) 

 working on Sagitta describes telosynapsis in spermatogenesis 

 and parasynapsis in oogenesis. King ('07, '08) describes' telo- 

 synapsis as occuring in the male and probably in the female 

 of Bufo. Arnold, '09, on Planaria finds no important distine- 

 tion between oogenesis and spermatogenesis. Wilson ('12) 

 has shown that in the case of Oncopeltus two different types 

 of conjugation may take place in one sex, i.e., the autosomes 

 unite by a parasynapsis while the sex chromosomes remain in 

 a massive condition and form no intimate union. He has also 

 pointed out that such conditions might explain the lack of 

 transference of hereditary factors between sex-linked groups 

 as is the case in the male of Drosophila (Morgan '12). It is also 



