222 TRANSMISSION OF ACQUIRED CHARACTERS 



(1) Many of the experiments and observations have failed to 

 conform to the ordinary canons of scientific method. Many of 

 them overlook the probability of coincidence, identify post hoc 

 with propter hoc, mix up observation and inference, or base a con- 

 clusion on a small number of instances. It may be noted that 

 cases suggesting the transmission of the results of mutilation and 

 injury are most abundant in the older, less critical literature. 

 What may be called good cases have been very scarce of recent 

 years, though many observers have been on the watch for them. 



(2) Some of the kinds of experiment e.g. the amputation of 

 large parts or of portions of internal organs, such as the spleen 

 are evidently of a kind which must be rare in nature. Therefore, 

 though such " fool's experiments," as Darwin would have called 

 them, may have some indirect value, they tend to be of little 

 significance to the evolutionist. 



(3) The experimental repetition of those mutilations and in- 

 juries which are common in nature is of little value, since nature's 

 experiment shows with sufficient clearness that the results are 

 not transmitted. If they were there would be but little now. left 

 of man and other combative organisms. As Hartog says, " The 

 tendency to transmit the mutilation itself would be so ruinous 

 as to rapidly extinguish any unhappy race in which it was largely 

 developed " (Contemp. Rev., v. 64, p. 55). As a matter of fact, 

 even in the individual lifetime the results of mutilation are very 

 often repaired by regeneration, which in its specialised expression 

 is probably the adaptive outcome of prolonged selection. 



(4) If the results of mutilation can be in any degree trans- 

 mitted, they must affect the germ-cells in some specific way. 

 The improbability of this is very great in the case of many 

 mutilations, such as lopping off. a tail. The amputation has often 

 little demonstrable effect beyond a slight irritation of the tissues 

 at the cut surface ; the organism's reaction bears little relation 

 to the actual effect produced ; a considerable part of the body 

 has been lost, but there is no constitutional disturbance the 



