PATHOGENESIS 283 



so much so that disease may be said to be primarily constituted 

 by a disturbance or distortion of symbiotic factors. Cessation 

 of biological symbiosis we found to mark the beginning of 

 pathological development. 



We have come across so many instances where disease had 

 to be viewed as the antithesis of symbiogenesis, that the old 

 maxim, " Pathologia Physiologiam illustrat," gained an 

 enhanced significance, and that the terms retrogression and 

 degeneration which we have already used as the obverse of 

 symbiogenesis became practically identical with " patho- 

 genesis." (Life may indeed be regarded as the field on which 

 the interplay of the constructional and progressive principle 

 of symbiosis with that of destructive and retrogressive anti- 

 biosis is carried on ; and this is, I believe, an illuminating 

 guide in all biological investigation and discussion.) 

 Retrogression and degeneration may be said to refer to the 

 more ultimate and obvious forms of biologically retrograde 

 redistribution of organic matter, resulting from long continued 

 pathological transmission ; pathogenesis to the principle of 

 debasing, by merely expedient abstractions or conversions of 

 materials, symbiogenetically noble into pathological and 

 biologically degraded developments. 



We have also seen the enormous physiological and bio- 

 economic importance of nutrition, and we have come across 

 instances of an urgent need of a change of diet in nature, 

 indicating that certain kinds of diet are not in the true interest 

 of the (indulging) species, but rather to the contrary. 



Perpetual in-feeding, involving the habitual ingestion of 

 biologically inadequate or superfluous food-substances, we 

 found to be " abhorred by Nature," heavy physiological and 

 biological penalties being exacted for all such offences. 



The modus opcrandi in this process we found to bear many 

 striking parallels to that of retribution in human polity and 

 showing that, as in the case of Gresham's law in the economic 

 world, bad physiological currency gradually drives out good 

 currency, thus leading to evils in various forms and tending to 



