34 HEREDITARY CHARACTERS 



have seen, however, that the alternative manner in which 

 the chromosomes are distributed before fertilisation takes 

 place, precludes the possibility of the characters common to 

 a race of individuals being represented in separate chromo- 

 somes, and as has already been said, there is not any good 

 reason to suppose that all characters are represented in 

 every chromosome and in no other part of the cell. 



On the evidence we have considered so far, however, 

 there is no reason to suppose that the nucleus as a whole 

 does not convey the hereditary characters, and all the 

 observations already quoted in favour of particular parts 

 of the nucleus may be used with equal justice in favour 

 of the nucleus as a whole. This theory has been, and still 

 is, held by many biologists. Professor J. A. Thomson says : 

 " The view has gained ground and general acceptance that 

 the nucleus is the chief or exclusive bearer of hereditary 

 qualities." l 



There is, however, a great deal more evidence that must 

 be taken into account, and this suggests that another opinion 

 may reasonably be held. 



Recent experimental work shows that there is much to 

 be said for those biologists who claim that the cytoplasm 

 bears an important part in conveying hereditary charac- 

 ters, and some of those who supported the view that the 

 chromatin was the only physical basis of inheritance at the 

 time that Wilson wrote the passage quoted above, have 

 ceased to adhere to the opinion expressed in it. Even the 

 broader view that the nucleus is the chief or exclusive 

 bearer of hereditary qualities is questioned by several 

 biologists of the highest standing, and there is some 

 reason to doubt the accuracy of the statement just quoted 

 from Professor Thomson as to its general acceptance. 



Meves has collected a great deal of evidence supporting 

 the view that the cytoplasm plays a very important part in 

 the transmission of hereditary characters. He points out 

 that a large number of observers have insisted upon the 



1 Heredity, p. 58, London, John Murray, 1908. 



