DEGENERATION OF FUNCTIONS 215 



a large store of nourishment in the body, or they live like 

 the Ephemera only a short time. 



Simple considerations of a general kind are sufficient to 

 show that the mere cessation of selection — sexual union with- 

 out selection — pammixis — cannot possibly be the exclusive 

 or even the principal cause of degeneration. It is a fact that 

 most organs reach com^pUU degeneration very slowly. But 

 their functional powers they lose very soon, and this can only 

 depend on the fact that they liegin to degenerate very soon 

 after they cease to be used, and to degenerate in the most 

 essential parts, in the co-ordination of these parts which is the 

 condition of the performance of the function. That the mere 

 morphological framework remains so long, and for such a 

 long time constantly reappears, is due to the persistence with 

 which characters acquired by the ancestors are repeated in 

 the descendants, — the morphological being inherited long 

 after the functional has been abandoned. The latter vanishes 

 lirst, and with it the essential existence of the organ. When 

 it has completely vanished, the organ can scarcely ever again 

 be recalled to the same activity — if the same function becomes 

 again necessary to the organism, it must hel^D to develop a 

 new organ. But I do not intend to exhaust this question 

 here, and will only point out that the loss of the function 

 means the loss of the most essential part of the organ, for 

 the form without contents is dead, worthless. Thus for us 

 degeneration is a certain result as soon as the function 

 has completely departed ; a revival of it is impossible. The 

 atrophy of the organ must then inevitably follow, step by 

 step ; however distant may be its completion, its occurrence 

 is certain. 



If the degeneration of functions, e.g. of instincts, took 

 place merely in consequence of the cessation of selection, 

 of pammixis, this degeneration, especially that of mental 

 characters, would proceed infinitely more slowly than it 



