1914] ELKINS—MATURATION IN SMILAX 43 
chromatic aggregations in the resting nucleus of Galtonia candicans 
and the number of chromosomes; moreover, in the telophase of 
the somatic divisions the chromosomes lose their identity, their 
centers dissolving and the chromosomes breaking into small 
portions. 
Many cytologists compromise on a middle ground and assume 
that bodies which are smaller than the chromosomes and into which 
the chromosome is divisible, are the chromatic units. These have 
been styled as pangens (MorrieR 29) or chromomeres (ALLEN 1, 
Lewis 24). In the ordinary use of the above terms the pangen 
represents a smaller unit than the chromomere; in this connection 
the terms are used simply to designate a small chromatic body of 
no determined size. The chromosome represents a definite group 
of these units and is probably formed for the purpose of facilitat- 
ing segregation and mitosis. ALLEN figures the actual union of 
chromatin granules in the spireme, with their subsequent separa- 
tion. Morrtrer finds no evidence of prochromosomes but supports 
the theory of the individuality of pangens. Lewis describes gran- 
ules in the resting nucleus in excess of the number of chromosomes. 
The differences among the above citations are not as serious as 
they might seem. By the adoption of a hypothetical unit smaller 
than the chromosome, it is not difficult to imagine that its ap- 
pearance, whether alone or in close approximation to its fellows, 
might vary and vary much with the different species of plants 
Studied. In the plants studied by Overton and Larsacu the 
chromosomes may be said to pass from one stage to another always 
In definite uniform groups, the prochromosomes. We may say 
these bodies maintain their permanence because of an unchan- 
ging mutual attraction of the chromomeres in each chromosome. 
We may conceive of another condition in which the mutual attrac- 
tion of the chromomeres in each chromosome group varies with 
the resting and active stages of the nucleus. Although RosEN- 
BERG (36) found the somatic number of chromatin bodies in the 
resting nuclei of the hybrid Drosera, he considered them as chro- 
matin centers about which chromatin units congregated in th 
Prophase, always with the same relative arrangement. This 
theory advanced by RosENBERG may be modified and extended to 
