90 VARIABILITY 



higher species, which can make but cannot transmit acquirements, 

 could not contend against them and would soon become extinct. 

 Again, the human being is capable of making only such use- 

 acquirements as evolution has fitted his race to develop. The 

 microbes, while they are becoming parasitic, are in an entirely new 

 and unfavourable environment, in which they are exposed to poison- 

 ing and enfeeblement through the enzymes secreted by the cells 

 of the host. Evolution has not adapted them to make the right 

 acquirements, any more than it has adapted human beings to make 

 acquirements fitting them for flight or for life under water. 

 Under the conditions, what sort of acquirements could they make 

 which would enable them to produce stronger and stronger and, 

 therefore, different toxins, and so protect themselves from the cells ? 



143. It is conceivable that the toxins might in some way be 

 enfeebled by injury to the producing apparatus and that this injury 

 might be transmitted and so accumulated in subsequent genera- 

 tions till the microbes perished ; but to believe that they are ever 

 strengthened, that the producing apparatus of the individual is 

 improved by the accidental effects resulting from the direct action 

 of the environment, is to believe in a coincidence, a 'fluke' so 

 remarkable that it amounts to miracle a miracle that must have 

 happened to every species of pathogenic microbe during its 

 transition from saprophyte to parasite, and which the human 

 operator is able to initiate at will by placing saprophytic species 

 in contact with living cells, a miracle as marvellous as if chance 

 blows of a hammer on pieces of metal had produced and fitted 

 together a delicate and elaborate machine. 



144. In brief, if saprophytic microbes, while becoming parasites, 

 are in any way affected by their new environments and doubtless 

 they are affected then, since they neither cause the extinction of 

 the species they attack nor themselves become extinct, it is certain 

 that their acquirements are not transmitted. The notion that, 

 like the higher animals, they are able to make use-acquirements, 

 is a mere guess, unsupported by any evidence, but opposed by 

 much. Even were the guess correct, then, since the higher or- 

 ganisms do not make acquirements which evolution has not fitted 

 them to develop, it is hard to understand how unicellular organisms 

 could react in a way that enabled them to meet contingencies 

 never before experienced by the race. The analogy between them 

 and the higher animals, therefore, is strained and inaccurate at all 

 points. 



145. Consider, now, the contrary hypothesis, that saprophytic 



