THE CHROMOSOME COMPLEX OF ORTHOPTERAN 



SPERMATOCYTES. 



C. E. McCLUNG.i 



A subject of perennial interest is offered by the maturing germ 

 cells, and that appreciation is not lacking is well evidenced by the 

 large annual output of papers devoted to different phases of the 

 question. The task of keeping abreast of this literature has be- 

 come a considerable one, especially since it is now necessary to 

 take into account the investigations upon hybrid matings and 

 upon unusual or modified methods of fertilization. Despite regret 

 at the increased labor thus brought about, one cannot but rejoice 

 at the enlarged conceptions of chromosome functions which have 

 followed from this union of two apparently different lines of in- 

 vestigation. 



It cannot be gainsaid, I think, that as our knowledge increases 

 it becomes more and more evident that in the chromosomes we 

 are dealing with intracellular elements of definite morphological 

 character which are self-perpetuating and which have to do with 

 the development of precise characters in the organism of which 

 they are a part. In my early study of the male germ cells of 

 insects I became convinced of this individuality of the chromo- 

 somes, and in all my papers I have emphasized this conception 

 and have brought forward proof in support of my position. ' It 

 is a pleasure to acknowledge here the material assistance that 

 has been rendered me in this endeavor by the consistent results 

 of my students. Realizing, however, the extensive character of 

 the problem, I have confined the work to a somewhat limited 

 field, but within this have made broad comparative studies. As 

 the work progressed there was indicated the prevalence of a 

 general plan of chromosome structure throughout the tracheate 

 Arthropoda studied and it then became necessary to undertake 

 careful researches within smaller groups, some of which have 



1 I am much indebted for assistance in carrying out work on Orthopteran germ 

 cells to the Carnegie Institution, which made grant No. 16 for this purpose. 



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