CHAPTER VII 



THE PRINCIPLE AS MANIFESTED AMONG 

 UNICELLULAR ORGANISMS 



IN the foregoing pages it has been from time to time 

 observed that the principle under discussion is a law 

 governing the union of sperm cell and ovum. We must 

 now see why this is so, and endeavour to gain a closer 

 insight into the nature of the principle. As the theory 

 was deduced from the theory of evolution, and as the 

 theory of evolution assumes the development of the higher 

 forms of life from minute unicellular organisms, it follows 

 that it should apply to the first beginnings of life among 

 these minute organisms. The sperm cell and ovum are 

 in the first instance nothing but specialised unicellular 

 organisms, and we may be confident that they will be 

 governed by the same general principles as the organisms 

 from which they were originally derived. So that, 

 although these organisms exist in enormous variety, and 

 although they are adapted to an enormous variety of 

 conditions, yet we should be able to trace, amid a vast 

 complexity of facts, some faint foreshadowing of our 

 principle. 



Unfortunately, the evidence available on this part of 

 the subject is very meagre. Nevertheless, such evidence 

 as there is tells with remarkable force in favour of the 

 theory. Before examining this evidence, however, it is 

 necessary to inquire to what rules we should expect the 

 conjugation of these unicellular organisms to conform. 

 We have seen that the higher organisms generally, among 



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