THE PHENOMENA OF LIFE 155 



which is simply ;i physico-chemical phenomenon exactly 

 analogous to gelatinous precipitation. Calcium phosphate 

 is always prone to coagulate; it lias been called the gelatinous 

 phosphate of lime, and we have already seen how readily 

 tribasic calcium phosphate takes the form of beautiful trans- 

 parent colloidal membranes which are gelatinous in texture. 



We may obtain colloidal precipitates exactly analogous to 

 coagulated albumin by mixing a weak solution of chloride of 

 calcium with potassium carbonate or tribasic phosphate. Like 

 albumin this precipitate forms flakes, and is deposited slowly 

 as a gelatinous colloidal mass. Like albumin also this calcic 

 solution is coagulated by heat; a solution of a calcic salt of a 

 volatile acid on heating forms a precipitate which has all the 

 appearance of albumin coagulated by heat. 



Finally, Arthus and Pages have shown that blood does not 

 coagulate when deprived of its calcium salts by the addition of 

 alkaline oxalates, fluorides, or citrates, and that the blood thus 

 treated recovers its coagulability on the addition of a soluble 

 salt of calcium. The coagulation of milk is also a calcium 

 salt precipitation. Coagulation therefore would seem to be 

 merely the colloidal precipitation of a salt of calcium. 



Diffusion and osmosis are the elementary phenomena of life. 

 All vital phenomena result from the contact of two colloidal 

 solutions, or of two liquids separated by an osmotic membrane. 

 Hence the study of the physics of diffusion and osmosis is the 

 very basis of synthetic biology. 



A living being exhibits two sorts of movements, those 

 which are the result of stimulus from without, and those 

 which are determined by an excitation arising from within. 

 In the higher animals the stimulus or exciting energy coming 

 from the entourage may be infinitely small when compared 

 with the amount of energy transformed. Moreover, the 

 response to an identical excitation may so vary as to give to 

 these different responses an appearance of spontaneity. There 

 is in reality no spontaneity, since the difference in response is 

 governed by previous external impressions which have left 

 their record on the machinery. There is in fact no such 

 thing as a spontaneous action, since every action of a living 



