252 
Sidney I. Kornhauser 
of a large nuniber of nuclei, many of them carefuUy drawn. The chromo- 
somes are well separated and stand out with a clearness not exaggeratcd 
by tlie drawings. The chromosomal counts were made exclusively from 
material fixed in Hermann’ s fluid, which gives the clearest imagcs. In 
no animal in which I have made counts was there to be found any 
Variation from the normal number. 
While there were deeply staining chromatic bodies in ihe quiescent 
nuclei of early generations of spermatogonia, these were of such variable 
size, shape, and number that it was impossible to establish the identity 
of any of them with the pair of sex chromosomes of the spcrmatocyte. 
Nor was there any constancy as to the size and number of chromatic 
nucleoli until the last spermatogonia! division was reached. Figure 14 
(Plate XIX) shows a condition characteristic for the quiescent nucleus 
of earlier generations. Xear the centre of the nucleus are found a few 
chromatic bodies, usually ill defined. In figure 17 (Plate XIX) — a 
quiescent nucleus of the last spermatogonial generation — a well defined 
chromatic body is present and also a less deeply staining clu'omatic nucleo- 
lus. These two chromatic bodies are found with great constancy, the 
less deeply staining one being often larger than the darker more compact 
body. This gives the first clew to the condition found in the growth 
period of the spermatocyte, where a single pair of chromosomes behaves 
differently from all the others. 
The chromosomes of the oögonia were studied in sections of young 
ovaries. While the number of counts made was not so large as in the 
case of the spermatogonia, owing to the difficulty of obtaining perfectly 
flat equatorial plates, stiU I feel quite certain that the number is twenty. 
Figurcs 25—28 (Plate XIX) represent cases in which there was not the 
least doubt as to the correetness of the counts made. While the size of 
the cells and of the chromosomes in the terminal chamber of the ovary 
is rather variable, yet the relative sizes of the chromosomes in a given 
cell compare exactly with those of the spermatogonia. In all cases the 
pair of macrochromosomes (dl) is very easily identified, and sometimes 
the second largest pair is also recognizable. As in the male, it is im- 
possible, from an examination of the diploid group, to recogmize any 
sex chromosome. 
B. Enehenopa curvata. 
The relation of the spermatogonia to the apical ceU is similar 
to that in E. binotata-, degenerating cysts are present also and show the 
same conditions as in E. binotata. Figures 11 and 12 (Plate XVIII) re- 
produce two successive sections cut at an angle of about thirty degi'ees 
