562 Gates.—The Trisomic Mutations of Oenothera. 
This leads to the question how far the chromosomes of Oenothera may 
be differentiated from each other. The conclusion is reached that the degree 
of differentiation probably varies in different organisms, being generally 
greater in animals than in plants. Such differentiation may be increased by 
the occurrence of Mendelian mutations, but in Oenothera mutations of this 
type are relatively infrequent. 
In conclusion, I wish to record my thanks to the Royal Society and the 
British Association for grants in connexion with this work, and also to the 
Royal Botanic Gardens, Regents Park, for the facilities afforded. 
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Reprint No. 12. 
