\ 



404 BIOLOGY AND ITS MAKERS 



out with such detail and apt illustration that if one follows 

 him step by step without dissent on some fundamental prin- 

 ciple, his conclusion seems justified. As a system it has 

 been elaborated until it makes a coherent appeal to the 

 intellect. 



Inheritance of Acquired Characters. — Another funda- 

 mental point in Weismann's theory is the denial that acquired 

 characters are transmitted from parent to offspring. Prob- 

 ably the best single discussion of this subject is contained 

 in his book on The Evolution Theory, 1904, to which readers 

 are referred. 



A few illustrations will be in place. Acquired characters 

 are any acquisitions made by the body-cells during the 

 lifetime of an individual. They may be obvious, as skill 

 in piano-playing, bicycle-riding, etc. ; or they may be very 

 recondite, as turns of the intellect, acquired beliefs, etc. 

 Acquired bodily characters may be forcibly impressed upon 

 the organism, as the facial mutilations practiced by certain 

 savage tribes, the docking of the tails of horses, of dogs, etc. 

 The question is, Are any acquired characters, physical or 

 mental, transmitted by inheritance? 



Manifestly, it will be difficult to determine on a scientific 

 basis whether or not such qualities are inheritable. One 

 would naturally think first of applying the test of experiment 

 to supposed cases of such inheritances, and this is the best 

 ground to proceed on. 



It has been maintained on the basis of the classical 

 experiments of Brown-Sequard on guinea-pigs that induced 

 epilepsy is transmitted to offspring; and, also, on the basis 

 of general observations, that certain bodily mutilations are 

 inherited. Weismann's analvsis of the whole situation is 

 very incisive. He experimented by cutting off the tails of 

 both parents of breeding mice. The experiments were 

 carried through twenty-two generations, both parents being 



