TRANSFORMISM 255 



least, such categories may only occur with a high degree of im- 

 probability (which ought to be capable of calculation.) If, then, 

 we make use of Mendelian results in the attempt to frame a 

 hypothesis of natural transformism we must again insert some 

 process that is anti-random into wild nature. 



86<:. The Hypothesis of Natural Selection. As formu- 

 lated by Darwin and Wallace the hypothesis is simple and very 

 logical. Briefly, the steps are as follows : organisms tend to 

 multiply to an indefinite extent, but their food-supply, shelter, 

 and even the space available to them are all strictly limited. 

 Therefore far more individuals come into existence, as eggs and 

 embryos, and survive for a short period as larv^, or juveniles, 

 than can possibly continue to exist long enough to reproduce again. 



There must, therefore, be competition among the organisms 

 of a race, or between those organisms and the individuals of 

 other races, for the limited food and shelter that nature provides. 

 This is " the struggle for existence." Now organic variability 

 (of whatever kind it may be) becomes a factor in the struggle. 

 There must be variants in the race-population that are larger, 

 more powerful, more speedy, with greater acuity of sense, with 

 mentalities that are more alert, etc. These variations must confer 

 advantage upon the animals that display them so that they will 

 be more successful in the struggle. Conversely there will be 

 individuals that display variations that are disadvantageous to 

 them. It is clear that, on the average, the variants that have 

 bodily advantages, in this way, will live longer and will reproduce 

 more often than those other individuals that have bodily dis- 

 abilities. Thus the " fittest " will tend to survive, while the 

 " unfit " will tend to be eliminated in the struggle for existence. 

 The conclusion, so far, is obvious and is valid whatever be the 

 nature of the variations that are of advantage, or are disabilities 

 — whether these variations are mutations that Mendelize, or are 

 fluctuations, or are acquirements. 



The next step in the argument is the questionable one. It 

 was assumed by Darwin, Wallace and their followers that all the 

 variations that naturalists can observe in wild organisms are 

 " inheritable," that is, that just these variations will reappear in 

 the progeny of the organisms in which we observe them. Let 

 us admit, for the moment, that this is true : then it can be shown 

 that transformism must occur. Let the graph A^ Fig. 35, repre- 



