333 



• Crooniax Lecture : The Bearing of Cytological Research on 



Heredity* 



By Edmund B. Wtlson, Da Costa Professor of Zoology, Columbia University, 



New York. 



(MS. received and Lecture delivered June 11, 1914.) 



The privilege of speaking ,^in this historic centre of learning was first 

 accorded to me more than 30 years'ago, through the extraordinary kindness 

 of Prof. Huxley to a young and unknown student. I would like to think it 

 more than a fancy that to the same source, possibly, I may trace the 

 distinguished honour of having been invited, after the lapse of many years, 

 to speak here once again on the subject of cytology in its bearing on 

 heredity. Of all Huxley's wise and felicitous sayings none has more per- 

 sistently lingered in my memory or appealed to my imagination than one 

 which vividly pictured, 35 years ago, the basic phenomenon that the 

 cytologist seeks to elucidate. Suggested, no doubt, by the researches of 

 Hertwig, Strasburger, and Van Beneden, then but recently made known, this 

 well-known passage is as follows : — 



" It is conceivable, and indeed probable, that every part of the adult contains molecules 

 derived from both the male and the female parent ; and that, regarded as a mass of 

 molecules, the entire organism may be compared to a web of which the warp is derived 

 from the female and the woof from the male. And each of these may constitute an 

 individuality, in the same sense as the whole organism is an individual, although the 

 matter of the organism has been constantly changing " (1878). 



The advance of modern cytology has been in some important respects a 

 development of the germ contained in these words. For the aim of cytology, 

 in so far as it bears directly upon the problems of heredity, is to trace out in 

 the individual life the history of maternal and paternal elements originally 

 brought together in the fertilisation of the egg. And the drift of latter-day 

 research, while it has not precisely confirmed Huxley's conception, has never- 

 theless been quite in harmony with the essential thought to which he gave 

 such picturesque expression at a time when the labours of cytology were but 

 just begun. 



This thought has been most nearly realised through the study of the cell 

 nucleus, and in particular of the bodies known as chromosomes. I ask 

 attention especially to these bodies in connection with certain problems of 



* It has been impracticable to reproduce here the original photographs and some 

 of the other figures by which the lecture was illustrated. 



