2 BIOLOGICAL LECTURES. 



diminution will be favored, for it will profit the individual not 

 to have its nutriment wasted in building up a useless structure." 

 Shortly after this Romanes advanced a not totally dissimilar 

 idea in his theory of the " Cessation of Selection " ('74). 



In 1890 Romanes revised his earlier views, calling especial 

 attention to the points in which they differed from those of 

 Darwin and Weismann, and in 1895, in his posthumous work, 

 the salient features of his theory are again indicated. Cope 

 carried the application from structures to species when he 

 wrote ('96) : " In other cases it is to be supposed that extremely 

 favorable conditions of food, with absence of enemies, would 

 have occurred, in which the struggle would have been nil. 

 Degeneracy would follow this condition also." 



But, without entering into the conflicting claims of origi- 

 nality and of priority, all the disputants are agreed that the 

 withdrawal of the supporting influence of natural selection from 

 an adapted organ or organism must or may, directly or indi- 

 rectly, lead to a condition of degeneration. That the arguments, 

 however, are too speculative in character is generally admitted, 

 and there is consequently demand for inductive evidence to prove : 



(1) That in a specific case, and in respect to certain charac- 

 ters, the operation of natural selection has been suspended. 



(2) That, when the operation of natural selection has been 

 suspended, increased variation occurs. 



(3) That, on the occurrence of (i) and (2), there is a departure 

 from a previously maintained and presumably high standard, and 



(4) That, unless a new equilibrium is established by adapta- 

 tion to the new environment, degeneration and perhaps final 

 elimination ensues. 



It would also be of incidental interest to learn from observed 

 facts whether the suspension of the action of natural selection 

 is felt immediately by an organ or organism; whether there is 

 any indication of " self-adaptation " tending to the establish- 

 ment of a new equilibrium; and whether this self-adaptation, if 

 detected, follows one or several definite lines. Of course, if the 

 evidence can be gathered from animals in a state of nature, 

 and if it can be checked by a large number of examples, so 

 much the better. 



