164 ROBERT T. HANCE 



the pull was applied. In other words, if the spindle fibre is attached 

 to the end of the chromosome or is telomitic (Carothers '17) 

 the daughter chromosomes pass to the poles as rods whereas if 

 the attachment is along the body of the chromosome or is atelo- 

 mitic then upon separation the daughters approach the poles as 

 V's with equal or unequal arms depending upon whether the fibre 

 is joined to the exact middle or to one side of the middle of the 

 chromosome. Figure 16 shows rods and V's which have already 

 reached the poles. Figures 84, 87 and 88 show rods V's with 

 equal and unequal arms approaching the poles. From the mate- 

 rial studied it may be said that the fibre attachment is in some 

 instances telomitic and in others atelomitic. More chromosomes 

 apparently have terminal fibre attachment than subterminal fibre 

 attachments. I oannot present complete evidence as to the con- 

 stancy of the point of fibre attachment in the pig but the similar 

 form of certain recognizable chromosomes (the longer ones) in 

 various cells would seem to indicate a permanency of the loca- 

 tion of fibre attachment. • 



A giant cell 



Figure 14 is a drawing of the chromosomes of a giant cell found 

 among the spermatogonia. The chromosomes at the right hand 

 end, as the cell has been placed on the plate, are somewhat 

 crowded and indistinct, but there are at least as many chromo- 

 somes as are figured. The number is seventy-four, which is just 

 six less than double the normal spermatogonial number. Since 

 the chromosomes do not appear smaller than those in the normal 

 cells and the chromosome number is nearly double that usually 

 found, it is believed that this cell has arisen, either through 

 the fusion of two spermatogonia or because separation of the 

 daughter cells failed to take place after the chromosomes had 

 divided. 



The recuced number of chromosomes 



Although no particular study has been made of the spermato- 

 cyte chromosomes, I have included two very clear figures at the 

 end of plate 2. Both of these show twenty chromosomes. Those 



