204 TRANSMISSION OF ACQUIRED CHARACTERS 



by any of the accidents and incidents in the daily life of the body 

 which is their bearer. But no one believes this, Weismann least 

 of all, for he finds the chief source of germinal variations in the 

 stimuli exerted on the germ-plasm by the oscillating nutritive 

 changes in the body. 



Weismann's Concessions. — There are some who find in this 

 " a concealed abandonment of the central position of Weismann," 

 and who say: "If the germ-plasm is affected by changes in 

 nutrition in the body, and if acquired characters effect changes 

 in nutrition, then acquired characters or their consequences 

 will be inherited." But it is quite illegitimate (§ 5) to slump 

 acquired characters and their consequences as if the distinction 

 were immaterial. The illustrious author of The Germ-Plasm has 

 made it quite clear that there is a very great difference between 

 admitting that the germ-plasm has no charmed life, insulated 

 from bodily influences, and admitting the transmissibility of 

 a particular acquired character, even in the faintest degree. The 

 point, let us repeat, is this : Does a structural change in a part 

 of the body, induced by use or disuse, or by change in surround- 

 ings, influence the germ-plasm in such a specific or representative 

 way that the offspring will thereby exhibit the same modification 

 that the parent acquired, or even a tendency towards it ? 



Determination of Sex. — In this connection reference has been 

 made to experiments such as those of Yung, who was able, by 

 altering the nutrition of tadpoles, to raise the percentage of 

 females from a normal of about 50 to about 90. Have we not 

 here an instance of an environmental influence playing in the 

 first place on the nutritive system, affecting the blood and 

 lymph, saturating through the body, and reaching the repro- 

 ductive system ? If the experiments are reliable, some tadpoles 

 which would have become males in natural conditions became 

 females under the stimulus of altered nutrition. 



It must be noted, however, that what was effected was not 

 the transmission of a modification, but an alteration of the 



