CHROMOSOME NUMBER AND PAIRS IN AMBYSTOMA 183 
form a series (fig. 31) like that (figs. 27 to 30) made by a similar 
arrangement of the chromosomes of normal cells (figures 1 and 
3). The length relationships of these chromosomes as shown 
graphically in figure 37 are practically identical with those of 
normal cells (figs. 33 to 36). Unfortunately, the cell walls are 
not visible. 5) Both of the homologues of chromosome pairs, 
as determined by measurements and indicated in figure 24 by a 
duplicate series of numbers, in some cases are found in the 
same separated part of the cell and in other cases one homologue 
is found in part a and the other in part b. 
The third case is a compact metaphase in the epithelium of 
the lung (figs. 26 A and B) and is similar to the second case. 
These two groups are somewhat more separated than those of 
figure 24. Figure 26 B represents the chromosome number and 
characteristics and figure 26 A shows the relative positions of 
the two groups omitting some of the chromosomes in a. 
That these two groups of chromosomes are parts of the same 
cell which have become separated is made highly probable by 
the following facts: 1) As in the second case (fig. 24), the two 
groups are near together, one containing eight and the other 
twenty chromosomes—a total of twenty-eight. 2) The chromo¬ 
somes are in the same stage of mitosis, the chromatids of those 
of b, however, being separated a little more than those of the 
twenty chromosomes in a which may be due to a less crowded 
condition. 3) The two groups are practically of the same 
diameter and of the same shape. An outline of a on transparent 
paper can be perfectly fitted to b. 4) These chromosomes also 
form a linear series of lengths (fig. 32) similar to those of normal 
cells. 5) Group a is not a complete cell because the cytoplasm 
can be seen only below the chromosomes, while above the 
chromosomes are bare. The boundaries of the cytoplasm of b 
cannot be seen. 6) The homologues of the chromosome pairs 
are numbered and distributed in the two groups like'those of 
figure 24. 
The fourth case is the peritoneum of another individual. It 
evidently is a cell which has been divided into two parts like 
those of cases 2 and 3. Figure 25 A is a camera-lucida drawing 
