686 C. E. McCLUNG 



that (1) it is difficult to determine exactly the spermatogonial 

 number, but it is probably 21 although his figure 17 shows 23 

 very clearJy. In the first spermatocyte, however, there are 10 

 tetrads plus the accessory chromosome. There is an individuality 

 of the chromosomes and spermatogonial elements reappear in the 

 first spermatocyte joined in pairs. (2) There are various forms 

 of the chromosomes due to the movements of their parts as well 

 as to the different aspects from which they are viewed. They 

 are conceived to be rods joined at one end and variously twisted 

 and separated. The union is slight and often they lie across each 

 other or one is bent around the other. Rings are loops, although 

 in figure 11a perfect annular element is shown, while crosses are 

 formed of overlying parts. (3) The forms of the prophase are 

 traced into the metaphase. (4) No clear polar views of the 

 metaphase are given, but in later views the paired elements are 

 shown placed one above the other — 'superposition' — with their 

 inner ends crossed. (5) In the dicession of the chromosomes 

 they move past each other going to the opposite pole of the spindle 

 from that side of the equatorial plate upon which they lay in 

 early metaphase. Whole spermatogonial chromosomes are thus 

 separated from each other by simply being pulled apart. (6) 

 Fiber attachment is terminal and to the spermatogonial deriva- 

 tive lying on the opposite side of the equatorial plate. (7) The 

 anaphase chromosomes are single V's whose contained space is 

 the longitudinal division established even as early as during the 

 anaphase of the preceding spermatogonial division. (8) By the 

 segregation of whole chromosomes in the first spermatocyte 

 there results a prereduction type of maturation. (9) The 

 V-shaped chromosomes of the anaphase are traced through the 

 interkinesis and into the second spermatocyte metaphase where 

 they are divided along the longitudinal cleavage of each, thus 

 constituting an equation divison. 



Gerard ('09) has studied only Stenobothrus and his results 

 may be compared in detail only with those of other investigators 

 upon similar material. Summarized, his findings are that (1) 

 while there is a loss of chromosome outlines after the last sperma- 

 togonial division and the formation of a network, there subse- 



