84 WARFARE IN THE HUMAN BODY 



It may seem an undue extension of the view that 

 pathology has played an immense part in evolution, if it is 

 suggested that it was upon pathological conditions that the 

 very existence of the Metazoa depended. There can be 

 no doubt that they originated from some protozoon by a 

 failure of normal physiological fission. We see here how 

 theories of disease may be modified according to the point 

 of view taken. From that, shall I say, of a protozoan 

 Hippocrates or Hunter nothing can be more obvious than 

 that a failure of mitosis would be a calamity, the birth of 

 a monster, of Siamese twins, among the normally con- 

 stituted unicellular organisms. It is still in the processes 

 of reproduction that we find the strongest evidence of the 

 part played by disease. 



When considering such problems in this light, it seems 

 somewhat difficult to account for the satisfaction of 

 many with the theory of small cumulative advantageous 

 variations. What ground is there for imagining such 

 machinery could result in a complex series of adaptations 

 such as the uterus, and what we may call its habits and 

 customs in dealing with the embryo from the entrance of 

 the ovum till birth ? Even those who adapt to their 

 own ideas some theory of large discontinuous variation 

 will, in the end, be compelled to attribute the uterine growth 

 and functions to a mystic power or virtue in the original 

 germ. They may follow some philosophers, and " unpack " 

 powers out of a conjurer's bag without telling us how 

 they got there. Yet if we regard the uterus as the result 

 of tissue reactions under abnormal stimuli, being guided 

 in research by the processes seen every day in disease, the 

 variations, whether small or large, continuous or discon- 

 tinuous, assume an aspect neither fanciful nor mystical, 

 and our need for biological faith is reduced to a decent 



