ON THE ORIGIN OF DEATH. II 3 



Among the Metazoa, however, the case is somewhat 

 different. In all the higher forms the germ-cells which 

 contain the potential immortality of the organism have 

 no function but that of reproduction, and are so well 

 protected from the environment that they must be diffi- 

 cult to affect. 



The old idea that an animal which strengthens its 

 legs by severe labor will have offspring with stronger 

 legs than one which has not so exercised is hard to 

 comprehend. If this be so, then we must imagine that 

 the strain put upon the muscle cells of the legs has 

 changed the molecular structure of the germ-cells. 

 This seems a monstrous supposition. Of course when 

 Weismann says that no acquired character can be in- 

 herited, he does not mean that half-starved animals 

 may not give rise to stunted young. This is, however, 

 a case of direct action on the young itself, for before 

 birth the young is fed from the tissues of the mother, 

 or the mother supplies food in the form of the egg-yolk. 



Certain diseases are known to be hereditary. These, 

 however, may perhaps be ascribed to the direct passage 

 of the Bacterium from the parent to the germ-cell or to 

 the embryo. Other diseases which are due to structural 

 malformation may, of course, also be inherited. The 

 isolated cases where scars or other such acquired char- 

 acters are said to have been inherited, are never so 

 well authenticated that their accuracy is beyond doubt. 

 Certain it is that where wholesale experiments on 

 animals have been carried on, no inheritance of mutila- 

 tions has been observed. Generations of horses and 

 dogs have had their tails docked without affecting their 

 young. The Chinese women deform their feet, yet the 



