254 RECENT CYTOLOGY 
water as containing oxygen and hydrogen, although 
the properties of these substances are completely in 
abeyance, so I believe it to be with equally good 
reason that our theory regards the individual chromo- 
somes as being preserved in the resting nucleus.’* 
Since Boveri expressed this opinion Rosenberg has 
produced further evidence of an equally convincing 
kind. He finds that in the case of certain plants the 
chromosomes do not pass over into a continuous 
reticulum during the resting condition of the nucleus, 
but remain separate, so that the same number of 
chromatic bodies can be counted during this stage as 
during the actual process of mitosis. 
Boveri has also produced evidence to show that 
different chromosomes play different parts in the 
economy of the organism. For example, when dif- 
ferent chromosomes were artificially removed from 
the nucleus of an embryonic cell by taking advantage 
of certain abnormal methods of division, the embryos. 
which arose from these cells developed to different 
extents and in different abnormal ways. 
This result is of particular interest, because it gives 
full corroboration to the suspicion, previously enter- 
tained, that the chromosomes are specially concerned 
with hereditary processes—with the building up of 
particular parts of the developing organism into shapes 
which resemble those of the corresponding parts dis- 
played by other members of the same species; and it 
seems further to show that particular chromosomes 
* Dr. T. Boveri, ‘Ergebnisse iiber die Konstitution der 
Chromatischen Substanz des Zellkerns,’ p. 22. 
