i897. HUMAN EVOLUTION. 307 



missible, then, it must be admitted, that the evolution of man and 

 every other complex animal is proceeding on enormously complex 

 lines — on lines so complex that it would be hopeless for any man to 

 attempt to delineate them in their entirety. But are they trans- 

 missible ? Mr. Buckman thinks they are. He writes : " The germ 

 is a unicellular organism, and therefore it should be modifiable in 

 accordance with its environment. Such environment would be 

 different in the body of a sedentary clerk, and of a hard-working 

 agricultural labourer ; and on this hypothesis the offspring in these 

 cases would be different." 



He misses the point at issue. It is not denied that changes in 

 the germ's environment {i.e., in the body of the parent) may result in 

 modifications in the organism into which the germ subsequently pro- 

 liferates ; but it is strenuously denied that acquired modifications in 

 the parent tend specially so to modify the germ as to cause the organ- 

 ism into which it subsequently proliferates to reproduce congenitally 

 the modifications which the parent acquired. To take a case men- 

 tioned by Mr. Buckman : " Visits to the Inventions Exhibition by 

 the mother during the period of gestation resulted in a child which, 

 unlike the others, has shown, since infancy, a remarkable mechanical 

 proclivity." So that Mr. Buckman contends that the slight cerebral 

 change in the mother so affected the child, situated on the other side 

 of the placenta and at the end of the long umbilical cord, that a much 

 greater cerebral change resulted in it. The seeing of inventions by the 

 mother rendered the child inventive. Surely this hypothesis, savour- 

 ing as it does of the miraculous, is unnecessary when we remember 

 how greatly twins or the individual members of a litter of puppies 

 (which cannot inherit different acquired traits from their parents since 

 the circumstances attending their genesis are precisely alike) may 

 differ mentally and physically. 



Several of my critics have declared that they are weary of the 

 endless controversy as to the transmissibility or non-transmissibility of 

 acquired traits. Not words but deeds are required, say they. Not 

 arguments, but careful physiological experiments. They are difficult 

 to please. It is impossible to imagine how physiological experiments 

 can be devised more profound and convincing than that enormous 

 series, conducted by the micro-organisms of disease, to which I have 

 called their attention. Thus, for example, for uncounted generations, 

 almost every individual in Europe, who has reached an age to propa- 

 gate his species, has acquired, through illness and recovery, immunity 

 to measles. Yet this acquired immunity, this profound constitu- 

 tional change, that not merely affects this or that organ, but the whole 

 body, has not in the slightest degree been transmitted. The European 

 child is as liable to infection as were the children of his remote 

 ancestors, or as are the children of Polynesians, who have only lately 

 been afflicted with the disease. He differs, however, from the Poly- 

 nesians, and presumably also from his remote ancestors, in that after 



