IO W. J. BAUMGARTNER. 



counted the number of rings and found 35 with six marked 

 doubtful. If we count one half of these we get 38, or just the 

 required number. This does not prove that there are always 

 two chromosomes that assume the ring shape, but it makes it 

 probable. 



A few facts can be added from the prophase stages that in- 

 crease the probability that these shapes are characteristic of the 

 individual chromosomes. Fig. 1 1 is a careful drawing made of 

 a cell in a late prophase. The nuclear wall is still intact. The 

 accessory is densely stained and smooth in contour. The ordi- 

 nary chromosomes are not yet compact or smooth in outline, but 

 they show many of the shapes appearing later. Counting the 

 chromosomes marked 6, which was drawn from the next section 

 and carefully identified as belonging to this cell, there are the 

 two rings, two crosses and several curved and bent rods. Fig. 8 

 shows a well-formed ring in an earlier stage. The formation of 

 the tetrads has not been studied in minute detail, since. this 

 has been done by McClung in the Acrididae (17) and Locustidae 

 (18), more favorable material for this part of the problem. Fig. 

 9 shows the chromatin rod with the longitudinal split indicated. 



Fig. 12 gives a polar view. The nuclear wall has just broken 

 down and the chromosomes have not been drawn into the equa- 

 torial plate. Here both ring chromosomes are visible which is 

 unusual for a polar view. Some of the other shapes can be seen. 

 I think that the chromosomes are not yet drawn by the fibers 

 and hence show these shapes from this view. Figs. 13, 14 and 

 1 6 and a, b, c in 18 show the diversity of forms that can be 

 made out in a single nucleus. The varied shapes can best be 

 seen in a nucleus just after the nuclear wall has broken down 

 and the chromosomes are being drawn toward the center. Fig. 

 13 and 1 8, a, are taken from cells in this stage. 



In Fig. 19 we have a drawing made from a smear preparation. 

 Again appear two rings, straight and bent crosses and rods. The 

 chromosome marked u has its ends crossed and thus forms a 

 modified ring. I think that this is a result of the pressure used 

 in spreading the cells on the cover, as I saw it on no other 

 slide. While the smear method shows the chromosomes well, 

 in none of my preparations so made does the spindle appear and 



