498 E. ELEANOR CAROTHERS 
SUMMARY OF OBSERVATIONS 
1. The so-called plasmasomes or nucleoli are always associated 
with certain spireme threads or prophase chromosomes; in these 
species they never exist as free bodies. This connection is through 
a peripheral, dense granule. 
2. During the growth period there are three of these vesicles, 
two single and one double. 
3. They occur at the distal end; that is, opposite the center 
of convergence of the chromatin threads of the loops formed by 
the union of the spermatogonial chromosomes. 
4. They have been found at all stages in the history of the 
germ cells, being visible even in the first spermatocyte metaphase, 
second spermatocyte telophase, and in the spermatids. 
5. Their staining power varies; but in general they stain most 
densely when the chromatin is most diffuse and give up this power 
as the chromosomes condense. 
6. The first maturation division is longitudinal for all the ordi- 
nary tetrads. This is proven by a knowledge of their structure 
gained from the prophase, by the point of attachment of the 
spindle fibers, and by the appearance of the rings during division. 
7. One of the tetrads which is associated with the accessory 
chromosome during the growth period divides transversely in 
the first spermatocytes and longitudinally in the second, which 
the accessory also does in effect. 
8. The dyads of this tetrad are nen in size, hence the 
chromosome is easily recognized. 
9. The different parts of this tetrad are distributed equally 
to both sorts of spermatozoa. 
DISCUSSION 
Sutton (02) showed that the spermatogonial chromosomes 
occur in pairs, and his conclusion was that in the somatic cells 
and in the spermatogonia there is a double series composed of 
homologous maternal and paternal chromosomes. This theory 
was put forward by Boveri (’01) but it remained for Sutton’s 
work to furnish direct evidence. These homologous pairs unite 
