56 SYMBIOGENESIS 



lacks the proper symbiotically obtained bio-chemical food- 

 stimulation, and is consequently in a permanent condition 

 of craving or hunger. It loses the sense of proportion, and is 

 driven frequently to make up by quantity what is lacking in 

 quality. Thus it becomes ravenous and gluttonous. As we 

 have already noted, Prof. Keeble states that marine animals 

 are always hungry ; but no doubt this applies to all animals 

 that are perpetual " in-feeders." 



The mole, a typical "in-feeding" terrestrial quadruped, 

 is an excessively voracious animal. It can endure no long 

 interval between meals, hunger soon ending in death. When 

 pressed by hunger, it will attack and devour even one of its 

 own kind, and its practice is immediately to tear open the 

 body of any bird or quadruped which it has killed, and, insert- 

 ing its head, to satiate itself with the blood. Such instances 

 can easily be multiplied. That we are dealing in such a case 

 with extreme morbidity, with an extreme parasitic diathesis, 

 seems hitherto not to have struck any naturalist. In their 

 opinion such instances represent normal life wild animals 

 being represented as having no diseases ! To look upon it 

 differently would be courting the very inconvenient necessity 

 for elucidating "the slippery basis of metabolism"! (It is 

 certainly courting " scientific " intolerance.) I have expressed 

 my conclusion on these matters thus: "Nature abhors per- 

 petual in-feeding," and the recognition of this most important 

 evolutionary law can no longer be shirked. There is startling 

 and overwhelming evidence in its favour on every side. Some 

 may be gleaned, for instance, from recent discoveries anent 

 the biological transmission of disease. 



The transmission of Plague by fleas, as reported in 

 Nature (19/3/14), provides an instance of the increasing 

 morbidity of the "in-feeding" habit once it has assumed the 

 proportions of a permanent parasitic diathesis, and of its 

 danger to the biological community in general. These most 

 laborious and well-set-out researches we owe to Mr. A. W. 

 Bacot and Prof. C. J. Martin. This is their conclusion : 



