CHROMOSOMES 237 



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. 



