1 68 TRANSMISSION OF ACQUIRED CHARACTERS 



as to the transmission of acquired characters — e.g. by the mor- 

 phologist His and the physiologist Pfliiger; but, as we have 

 said, the focussing of the question was due to Galton and 

 Weismann. 



Galton. — Thus Galton in 1875 stated his opinion that the 

 current theory of the inheritance of characters acquired during 

 the lifetime of the parents " includes much questionable evidence, 

 usually difficult of verification. We might almost reserve our 

 belief that the structural cells can react on the sexual elements 

 at all, and we may be confident that at the most they do so in 

 a very faint degree — in other words, that acquired modifications 

 are barely, if at all, inherited in the correct sense of that word." 



Galton's position at that time may be summed up as follows : 



( 1 ) In regard to climatic variations, Galton doubted the reality of 



any reaction of the " body " upon the germs, but believed 

 that the germs are themselves directly affected. 



(2) The same is true in regard to many diseases that have been 



acquired by long-continued irregular habits. 



(3) The cases of the apparent inheritance of mutilations are out- 



numbered by the overpowering negative evidence of their 

 non-inheritance. 



(4) It is hard to find evidence of the power of the personal structure 



to react upon sexual elements that is not open to serious 

 objection. That which appears the most trustworthy lies 

 almost wholly in the direction of nerve changes, as shown 

 by the inherited habits of tameness, pointing in dogs, 

 and the results of Dr. Brown-Sequard's experiments on 

 guinea-pigs. 



Weismann. — But Weismann gave the scepticism an even 

 sharper point. He denied all transmission of acquired modifi- 

 cations, partly because he found the evidence so flimsy and 

 anecdotal, partly because he could not conceive of any mechanism 

 whereby the transmission of a particular acquired modification 

 could be effected, and partly because his whole theory of heredity 

 and variation raised strong probabilities against the view that 



