WENRICH: spermatogenesis of PHRYNOTETTIX MAGNUS. 59 



plished, the two opposing views that have been most wudely discussed 

 are: — (1) that homologous chromosomes unite side-by-side (para- 

 synapsis), or (2) that they unite end-to-end (telosynapsis). The 

 adoption of either view, however, involves the very important assump- 

 tion that there is a continuity between the chromosomes that appear 

 in the earlier divisions and those that conjugate. Doubt has been 

 expressed by some writers as to the existence of any such continuity, or 

 individuality, of the chromosomes, and the question is regarded as 

 one that is still unsettled. Many geneticists, on the other hand, are 

 readily inclined to correlate the behavior of the chromosomes in 

 maturation with the behavior of Mendelian factors in heredity. And 

 in some cases an organization of the individual chromosomes has been 

 assumed of such a nature that a definite portion or region of a chromo- 

 some is concerned with the transmission of a particular factor. Such 

 assumptions call for an analysis of the individual chromosomes to 

 determine their inner constitution or architecture. 



The author of the present study has sought to throw light on all 

 these problems. That as to how synapsis takes place was the first 

 considered; it was taken up from the standpoint of the origin and 

 constitution of the chromosomes of the first spermatocytes. Early 

 in the work it was found that the only method by which conclusive 

 results could be obtained was that of following the history of individual 

 chromosomes. Owing to the favorableness of the material, at least 

 three chromosome-pairs were found that possessed individual peculiari- 

 ties by which they could be recognized through all stages from the 

 growth-period to their division in the first spermatocyte mitosis. 

 Pursuit of this method naturally led to a consideration of the problem 

 of the individuality of the chromosomes, and it was found to be possi- 

 ble to recognize one pair of chromosomes at all stages from sperma- 

 tognia to spermatids. A further study of chromosome-individuality 

 led to the interesting discovery that each chromosome has a definite 

 organization, or architecture, which appears at the same stages in all 

 the animals studied. 



In the following description, I have not followed the usual method 

 of adhering to the chronological seqvience of events, but have adopted 

 the order in which the problems presented themselves. I believe I 

 have been able through a study of this material to demonstrate that 

 in Phrynotettix (1) parasynapsis occurs, (2) usually the first matura- 

 tion is equational, (3) each chromosome preserves its individuality 

 throughout the spermatogenic cell-generations, and (4) at least cer- 

 tain chromosomes, and probably all, have a recognizably constant 

 organization. 



