690 C. E. McCLUNG 



proximation of the two threads. Smaller elements may fail, or 

 be unable, to form rings and then appear as straight rods. Such 

 rods then break across at the middle and form tetrad-like chromo- 

 somes. Sometimes at the middle point the halves of the threads 

 are drawn out to form cruciform chromosomes. (3) The various 

 prophase forms are traced directly into the metaphase through a 

 gradual condensation. (4) The rings lie in the spindle parallel 

 with its axis; the rod-shaped forms are extended in the same 

 manner. (5) A mere separation of the half rings or half rods 

 is all that occm's in the metaphase. (6) In the case of the rings, 

 fiber attachment is at the middle of each half ring, in the rods at 

 opposite ends of the extended structure. (7) Forms shown 

 by the anaphase chromosomes are split half rings from the annu- 

 lar chromosomes and V's from the rods. (8) By the first sper- 

 matocyte division one end of each of the spermatogonia! chromo- 

 somes, joined side by side in the prophase, is separated from the 

 other end and goes into a different second spermatocyte. It is 

 not a reduction or segregation division because homologous ele- 

 ments are not separated; it is not an equation division for the 

 reason that not all parts of each chromosome are represented 

 in the daughter cells. As described by Otte it is an entirely 

 unique form of division. (9) The second division is like the 

 first, even to the fonns of the chromosomes. Before the second 

 spennatocyte metaphase the half rings have again become rings 

 and are once more separated as in the preceding mitosis. The 

 rods are again divided transversely and go to the poles as split 

 rods. This also is neither a reduction nor an equation division. 

 The result of the two divisions is to divide each spermatogonia! 

 chromosome, joined by parasynapsis to its homologue, twice 

 transversely, one-fourth of its length going into each spermatid. 



Stevens ('12) discusses supernumerary chromosomes and the 

 method of synapsis in Ceuthophilus. She finds a parasynapsis, 

 subtemiinal fiber attachment and a reduction division in the first 

 spermatocyte. 



Vejdovsky ('13), together with studies upon Ascaris, Gordius 

 and other genera, has reported the results of his investigations 

 upon Decticus and Diestramena, two Locustid genera. His 



