226 SYMBIOGENESIS 



bio-economic part to perform in the web of life. That this part 

 is not the same as that of the crystalloids is evidenced by the 

 fact that they are insipid whilst the latter are "sapid." 

 There is a natural antagonism between the two, but we may 

 conclude that for normal purposes they should not be 

 antagonised to an extreme extent. 



If the evolution of taste and of smell is due, as Spencer's 

 passage almost suggests, to the protracted and cumulative 

 inter-action between crystalloid particles and the respective 

 nerve-matter, the question naturally arises which food sub- 

 stances are the most fitted to promote by adequate chemical 

 stimulation the progressive development of these important 

 senses, which are as guides in the selection of foods. Obviously 

 the indispensable nutrition must convey at least a sufficient 

 modicum of crystalloids in some shape or other. At first sight 

 this requirement would seem to clash with the observation that 

 the great bulk of our wholesome natural food is constituted by 

 colloids. The fact that living substance or protoplasm always 

 takes the form of colloidal solution man himself, like every 

 other organism, being but a complex of colloids also seems to 

 point in favour of colloids rather than of crystalloids for food 

 purposes. In a colloidal solution, however, as Prof. Schaefer 

 pointed out in his presidential address before the British 

 Association at Dundee (1912), "the colloids are associated with 

 crystalloids (electrolytes), which are either free in the solution 

 or attached to the molecules of the colloids." (Italics mine.) 



"In a living substance," he further tells us, "the 

 presence of certain inorganic salts is essential, chief amongst 

 them being chloride of sodium and salts of calcium, 

 magnesium, potassium and iron." ..." The combina- 

 tion of these elements (their co-operation, as I would add) into 

 a colloidal compound represents the chemical (and incipient 

 symbiotic!) basis of life." 



Moreover, we must bear in mind that the most important 

 colloids for purposes of animal nutrition are the so-called 

 emulsoids (Emulsion-colloids), a group which in many respects 



