Organic Evolution. 185 



valueless to the species, but they are even harmful, for 

 they take the places of those which are sound. Hence, by 

 the operation of natural selection, the life of our hypo- 

 thetically immortal individual would be shortened by the 

 amount which was useless to the species. It would be 

 reduced to a length which would afford the most favourable 

 conditions of existence of as large a number as possible of 

 vigorous individuals at the same time." This may be so, 

 but, as it stands, the modus operandi is not given, and is 

 not obvious. We start with a hypothetically immortal 

 metazoon. Barring accidents, it will go on existing in- 

 definitely. But you cannot bar accidents for an indefinite 

 time; hence, the longer the individual lives, the more 

 defective and crippled it becomes. There is neither natural 

 decay nor natural death here. The organism is gradually 

 crippled through accident and injury. But the crippled 

 individuals are harmful to the species, because they take 

 the places of those which are sound. Therefore, says 

 Professor Weismann, natural decay and death step in to 

 take them off before they have time to become cripples. 

 Now, the point I wish to notice is that there is no definite 

 statement how or why natural decrepitude should thus 

 be introduced. We must remember that it is not until a 

 late stage in evolution that, through the association of its 

 members, groups of organisms compete with other groups. 

 In the earlier stages, when we must suppose decrepitude 

 and death to arise on Professor Weismann's hypothesis, the 

 law of the struggle for existence is each for himself 

 against all. The question, therefore, is What advantage 

 to the individual is there in natural decay and death to 

 enable it, through the possession of these attributes, to 

 escape elimination ? Surely none as such. At the same 

 time, it is quite conceivable that natural decay and death 

 may be the penalty the individual has to pay for increased 

 strength and vitality in the early stages of life. This, 

 probably, was Professor Weismann's meaning. But, if so, 

 it Would surely have been better to state the matter in 

 such a way as to lay the chief stress on the really important 



