THE CHROMOSOMES 151 
Tue INDIVIDUALITY OF THE CHROMOSOMES 
The view that the chromosomes are persistent as 
individual structures in the cell has steadily gained 
ground during the last twenty years. The process 
of karyokinetic or mitotic division by means of which 
at each cell division the halves derived from a length- 
wise split of each chromosome are carried to opposite 
poles, so that a genetic continuity is maintained be- 
tween corresponding chromosomes (and parts of 
chromosomes) in mother and daughter cells, has been 
found to be almost universal in both plants and 
animals. It is true that several instances have been 
described in which the nucleus simply pinches into 
two parts, and there can be little doubt that such cases 
occur; but no one has been able to show in a convinc- 
ing way that cells which have once divided in this 
manner ever return to the regular process of karyo- 
kinetic division. Case after case of amitosis that 
has been described for the germ cells has been either 
disproven, or found to rest on faulty observation, or 
else to relate to cells like those of the egg coats that 
take no part in the germinal stream. 
There are several observations that lead to the 
view, at present generally accepted, that the chromo- 
somes retain their individuality from one cell division 
to the next. These may now be given. 
During the resting stage the chromosomes spin out 
in such a way that they appear to form a continuous 
network in the nucleus. They can not be identified 
individually during this period. When the chromo- 
