CHROMOSOMES OF INDIAN RUNNER DUCK. 337 



other point and in some cases at least, they are constant in posi- 

 tion. For example, Sakamura ('16) found that in Vicia several 

 of the chromosomes show a constant subterminal constriction 

 and that those of one pair show a constant median constriction 

 in addition. However, Agar ('12) found in Lepidosiren that these 

 sutures vary in position in different chromosomes and that they 

 correspond with the points of attachment to the spindle and 

 that their position in the chromosome of the meiotic division 

 corresponds with that in the spermatogonial chromosomes. 

 Wilson, however, points to the fact that these sutures and con- 

 strictions are visible in the prophase before the spindle is formed 

 and therefore are not caused by the attachment. That these 

 sutures may not be necessarily connected with the attachment of 

 the traction fibers is shown by the No. 37 chromosomes of my 

 material. Here there are two sutures, one at about one twelfth 

 of the length of the chromosome distant from one end and the 

 other at about one fourth the length of the chromosome distant 

 from the other end. It is hardly probable that there would be 

 two traction fibers so widely separated arising from the same 

 somatic chromosome. 



Again it should be pointed out that the permanence of position 

 of such sutures at at least two different points along such chromo- 

 somes (see Fig. 23) would seem to be morphological evidence that 

 such chromosomes differ in a qualitative way throughout their 

 length. 



So far, we have been following the characteristics, sizes, etc., 

 of the largest chromosomes. Let us next consider the chracter- 

 istics of the chromosomes of the intermediate group. There are 

 nine of these (Nos. 32 to 24) and they are of the short rod-shape 

 type. Among these is one pair, the members of which are some- 

 times seen as crescent-shaped bodies (Fig. 8, cr.). Altogether 

 the nine pairs form a closely graduated series ranging in size from 

 those somewhat shorter than the shortest in the foregoing series 

 to short ones that are almost as thick as they are long, but 

 certainly distinguishable as rods by their acute angles (Figs. 



43-48). 



The third group of chromosomes consists of forty-six round or 

 globe-shaped bodies (numbers 23-1). These also form a closely 



