THE SPERMATOGENESIS OF APLOPUS MAYERI. 



BY H. E. JORDAN. 



INTRODUCTION. 



The object of the present investigation is primarily to trace the history 

 of the accessory chromosome through the various stages in the process of 

 spermatogenesis in the phasmid Aplopus inaycri. Incidentally an effort is 

 made to present in as concise a form as appears compatible with complete- 

 ness the several salient points of similarity and difference between the 

 growth and maturation phenomena as they obtain in Aplopus and other 

 Orthoptera previously studied. 



The study of the accessory chromosome is approached from the stand- 

 point of its possible relation to the determination of sex as first suggested 

 by McClung (1901), and its support of the hypothesis of the morphological 

 and physiological individuality of the chromosomes as enunciated by Rabl 

 (1885) and later extended by Boveri (1902), Sutton (1902), Montgomery 

 (1904), Baumgartner (1904), and others. 



This study purports to be mainly a cytological one. The microscopic 

 anatomy, as also the anatomical relations of the gonads of Aplopus mayeri, 

 is essentially similar to that so well described and illustrated by de Sinety 

 (1901) in the case of Leptinia attenuata and Menexcnus obstusespinosus. 

 Nor shall I here attempt a review of the literature on the subject of the 

 " heterochrosomes " (Montgomery, 1901). This has been very excellently 

 done by several cytologists (Sutton, 1900; McClung, 1902; Montgomery, 

 1904) and more recently and very completely by Boring (1907). 



It seems necessary to state at this point only that the chromosome, for 

 which I have adopted McClung's (1901) terminology, "accessory chromo- 

 some," has been described as a closely similar structure in many of the in- 

 sects, especially the Hemiptera, under the several names of " odd chromo- 

 some " (Stevens); " chromatin nucleolus " (Montgomery); "chromosome 

 speciale " (de Sinety) and " heterotropic chromosome" (Wilson). 



MATERIAL AND METHODS. 



The material upon which the investigation is based was obtained from 

 Loggerhead Key, Florida, through the kindness of the Carnegie Institution 



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