CHROMOSOME COMPLEX OF SPERMATOCYTES. 



315 



of the prophase with one of the tetrads occurs. This is brought 

 about by the end to end union of the parts which produces a 

 pentivalent chromosome, or decad. So far as I know no such 

 a chromosome as this has ever before been described. 



The metaphase exhibits this 

 strikingly peculiar chromosome 

 extended along the length of the 

 spindle parallel to its axis. The 

 terminal parts are variously 

 placed, sometimes being bent 

 back parallel with the middle 

 portion, sometimes extending 

 out at right angles to it, and 

 again being directed upward at 

 an obtuse angle. Frequently 

 the two terminal elements are 

 differently inclined to the middle 

 portion. In any event the archo- 

 plasmic fibers attach, not at the 

 free ends of these chromosomes, but where their other ends join the 



FIG. 10. Lateral view of some of 

 the chromosomes in the metaphase of a 

 spermatogonium of Mermi^ia. The 

 multiple chromosome shows its tetrad 

 character well. 



FIG. II. Prophase of first spermatocyte of Mermiria showing particularly the 

 accessory chromosome attached to a tetrad as in Hesperotettix. The organization of 

 the cytoplasm is also indicated. 



main shaft of the element. One point which I have not yet been 

 able to determine with certainty is the position of the accessory 



