700 C. E. McCLUNG 



any loss of identity, from the spermatogonium over into the 

 first spermatocyte. It was at first regarded as very different 

 from the other chromosomes and was described as a nucleolus 

 by many, but longer study has taught that it parellels the euchro- 

 mosomes, although in a modified form, in every part of its history 

 except in actual synapsis. That one of the spermatogonial 

 complex, in most cases slightly distinguishable from its fellows 

 throughout the 'division period,' should pass into the first sper- 

 matocyte without loss of form or identity and there perform much 

 the same evolutions as the others, while still remaining distinctly 

 delimited, is a very strong piece of evidence for the individual 

 continuity of the others. 



I believe therefore that it may fairly be said that the evidence 

 from Orthopteran studies is strongly in favor of the view that the 

 chromosomes of the last spermatogonial mitosis pass over as 

 such into the first spermatocyte where they appear joined together 

 in pairs. As I have stated elsewhere this seems to me a funda- 

 mental conception, for unless we are dealing with structures of 

 definite and characteristic organization their manoeuvres in 

 maturation are of small moment. In the further discussion it 

 will therefore be assumed that the establishment of the concept 

 of chromosome continuity has been made with a reasonable degree 

 of certainty. This being done we have next to consider the 

 method of association set up in the first spermatocyte chromo- 

 somes and the forms through which it is manifested. 



b. Composition of chromosomes in the first spermatocyte prophase 



A thoroughgoing consideration of the composition and form 

 of the first spermatocyte chromosomes would require a full analy- 

 sis of the complicated series of changes through which the chromo- 

 somes pass after the last spermatogonial division, when they enter 

 into the tetrad condition. This cannot be done, for we are yet 

 lacking a sufficient knowledge of these stages. We can but 

 regard the haploid group of the first spermatocyte prophase and 

 find therein the recognizable members of the unreduced complex, 

 which, as I have shown elsewhere, may be accomplished very 



