398 EDMUND B. WILSON 



undivided threads. The F-figures are not opening apart, they 

 are closing up, as is placed beyond doubt by the magnificent 

 demonstration of the seriation given in the testis of Batracoseps. 

 F-figures with a short stem and long arms precede, they do not 

 follow, those with long stem and short arms. What is taking 

 place is evidently a coming together of the thin threads side, by 

 side in pairs to form the thick ones — a process exactly opposite 

 to longitudinal division. I do not hesitate, therefore, to confirm 

 positively the description of the facts given by Janssens and the 

 Schreiners. 



I desire to emphasize the striking contrast that exists between 

 the amphitene-nuclei and the spermatogonial or other diploid 

 prophase-nuclei. It seems to me that Meves goes much too far 

 when he directly compares the process of 'parallel conjugation' 

 to the early fission of spireme-threads in the diploid nuclei as 

 described by Flemming and his successors ; for one is led from this 

 to suppose that figures may be seen in the two cases that are 

 essentially similar. But no one can study the early spermatogonial 

 prophases in Tomopteris or Batracoseps without being struck 

 by the very great contrast which they present to the amphitene- 

 nuclei.^^ Never in the former case, as far as 1 have been able to 

 find, are the two halves of the double spireme-threads seen diverg- 

 ing like the branches of a F; nor have I been able to discover such 

 pictures in the early prophases of other diploid nuclei, such as 

 the epithelial and connective tissue cells of larval salamanders. 

 Even though such pictures could be found, the amphitene nuclei 

 undeniably offer peculiarities that differentiate them in the most 



1* In considering this question it is necessary to point out that the single figure 

 of the amphitene stage that Meves offers in favor of his interpretation ('07, text- 

 figure, p. 460) conveys no real idea of the characteristic relation of the leptotene- 

 threads to the pachytene. Many pictures similar to this are seen in my own sec- 

 tions of Batracoseps and Plethodon, especially after fixation by Flemming's fluid 

 or Hermann's, often also in inferior preparations from Carnoy's fluid; but as a 

 rule it is only in the best Carnoy preparations that the exact relations can be 

 clearly and generally seen. It is evident that the least defect due to fixation or 

 to the shrinkage of embedding process tends to obscure the leptotene-threads and 

 cause them to assume a more netlike appearance. 



