CHAPTER III 



ARE ACQUIRED CHARACTERS INHERITED ? 



Evidence from ovarian transplantation experiments with 

 guinea-pigs has been cited to show that body and germ-cells 

 are morphologically and physiologically distinct and that 

 germ-cells may be lodged in a foreign body during their de- 

 velopment without losing their distinctive character. But 

 this by no means proves that germ-cells are immune from 

 modification by influences which reach them through the 

 body. The evidence cited is negative evidence. It creates a 

 presumption against the inheritance of acquired characters 

 but does not prove a universal negative, which is impossible. 

 The question whether acquired characters are or are not in- 

 herited is therefore a question to be decided only by the care- 

 ful weighing of evidence. It is possible that some categories 

 of supposed acquired characters are more readily capable of 

 an alternative interpretation than are others. Several of 

 these may now be discussed briefly. 



1. Mutilations. It is now all but universally admitted 

 that somatic modifications due to mutilation are not in- 

 herited. Nevertheless " cases " are from time to time re- 

 ported, in which a man or a domesticated animal which by 

 accident had lost a limb has produced offspring similarly de- 

 fective. One of the most frequently recurring of these stories 

 has come to me at first hand. A cat which had accidentally 

 lost her tail gave birth to kittens part of which were short- 

 tailed. It is not necessary to suppose that the report is in- 

 accurate. Certain races of cats are naturally short-tailed, 

 and a cat might produce offspring short-tailed by inheritance 

 quite irrespective of any injury to either parent. On the 

 other hand where docking of the tail has been followed up 

 systematically for many generations and on a large scale, as 

 is the case in sheep, no racial shortening of the tail is observ- 

 es 



