CHROMOSOME COMPLEX OF SPERMATOCVTES. 



321 



sibility of an association of the accessory chromosome with one 

 of the bivalent structures of the first spermatocyte I was soon 

 able to see that the peculiar chromosome of Anabms was another 

 such a multiple chromosome as that of Hesperotettix. There is 

 this difference between them, however, that in Hesperotettix the 

 accessory chromosome is the small, univalent element, while in 

 Anabnts it is proportionately very large, causing the tetrad with 

 which it is associated to appear as an appendage at one end. 



The multiple chromosome of Anabnts is a striking illustration 

 of a fact to which I have often made reference, /. e., to the 

 relation existing between chromosomes and the attached archo- 

 plasmic fibers. /// all tetrad elements the fibers are annectent at 



IMG. 19. Oblique view first 

 spermatocyte of Anabrus in meta- 

 phase in which appears a multiple 

 chromosome consisting of the acces- 

 sory chromosome "a.c." and a 

 small tetrad, several small tetrads 

 and the one large one. 



FIG. 20. Lateral view of first 

 spermatocyte of Anabrus in meta- 

 phase exhibiting the same structures 

 represented in the preceding figure. 

 Note the attachment of the fibers 

 to the hexad. 



the fused ends of tJie chromosomes, representing the plane of the 

 future reduction division, and never at the free ends. When the 

 accessory is added to a tetrad in Hesperotettix the arrangement is 

 disturbed somewhat in order to allow the insertion of one fiber to 

 the point of contact between the accessory chromosome and one 

 member of the tetrad, while the fiber to the other centrosome 

 finds its connection at the free end of the tetrad. 



Such a condition obtains also in Anal-rns resulting in the pro- 

 duction of a very singular appearing chromosome. Since the 

 accessory is so very long it seems as if the fibers from both cen- 

 trosomes attach near one end of the multiple chromosome, but as 



