58 SYMBWGENESIS 



"A. flea once infected has very little prospect of future happi- 

 ness." This is well put, although the substance of it and its 

 wide bearing as a general biological and sociological principle 

 was already known to Dean Swift : 



Great fleas have little fleas, and lesser fleas to bite 'em, 

 And these fleas have other fleas, and so ad inflnitum. 



That the rat flea thus becomes an intermediary of disease 

 only again shows that anti-symbiotic instincts in course of time 

 must set up a vicious circle the rat in turn being a most 

 voracious and most unclean " in-feeder." "Shall they not 

 rise up suddenly that shall bite thee, and awake that shall vex 

 thee, and thou shalt be for booties unto them "? 



An " in-feeder" may be said to rely upon inferior (second 

 or third hand) physiological currency, and this means, as I 

 have shown in previous volumes, that by an operation analogous 

 to that of Gresham's law of currency, the superior physio- 

 logical currency is gradually driven out from the physiological 

 economy of the species. The result is physiological bankruptcy 

 with concomitant loss of good character and ensuing 

 criminality judgment turned into gall, and the fruit of 

 righteousness into wormwood. 



The importance of good physiological currency and 

 associated habits, however, is only very partially realised by 

 our investigators. Prof. Keeble very tentatively suggests that 

 in C. roscoffensis the algae may produce and supply a hormone 

 " entrusted by custom (italics mine) with the task of signalling 

 to the animal to proceed with the business of ordered develop- 

 ment." Thus, at any rate, we get the idea that what measure 

 of "ordered development" there is in an animal, depends on 

 "customary" supplies of "signalling substances" by the 

 symbiotically related plant. But is this all? Is it only due to 

 the quite recent discovery of such minute and as yet very little 

 known substances as "hormones" that we can know anything 

 about the true relations between plant and animal a matter 

 upon which our whole existence depends? 



