THE ORGANIC CELL 
88 
ends form corresponding lobes of the nucleus. During the 
following division the chromosomes make their appearance 
in the same position, their ‘ends lying in the nuclear lobes 
as before.’ From this and similar evidence, the chromosomes 
must be looked upon as elementary organisms, leading an 
independent existence in the cell. 
Evidence of the Individuality of the Chromosomes. 
Abnormalities in the Fertilisation of Ascaris. (Boveri.) 
A. The two chromosomes of the egg-nucleus, accidentally separated, have 
given rise each to a reticular nucleus ( $ , $ ) ; the sperm nucleus below ( $ ). B. 
Later stage of the same, a single chromosome in egg nucleus, two in the sperm 
nucleus. C. An egg in which the second polar body has been retained ; p.b 2 . 
the two chromosomes arising from it ; $ the egg ••fcromosomes ; S the sperm 
chromosomes. D. Resulting equatorial plate with six chromosomes. 
Boveri, applying this reasoning to the fertilisation of the egg, 
came to the conclusion that ‘ we may identify every chromatic 
element arising from a resting nucleus with a definite ele- 
ment that entered into the formation of that nucleus, from 
which the remarkable conclusion follows that in all cells 
derived in the regular course of division from the fertilised 
egg one half of the chromosomes is of strictly paternal origin, 
the other half of maternal.’ 
Boveri’ s hypothesis was severely criticised at the time, 
Vol. V.— No. 9. D 
