I 



THE PHYSICAL BASIS OF LIFE 191 



Rejuvenescence can be brought about by a great variety of 

 media, by extracts of muscle, of brain, of pancreas, by simple 

 salts, by alcohol even. It is not food, but a marked and abrupt 

 change of state that is needed — a stimulant, in fact — and beef 

 extract produces its effect not qua food, but as a stimulant 

 pure and simple. Senile decay is due to monotony, under the 

 influence of which the vital potential wears out ! 



The action of alcohol is remarkable. It was added to the 

 water in which the animals lived so that they were always 

 immersed in a solution of 1 part of spirit in 5,000 to 10,000 

 of water. In the effect produced there is the touch of nature 

 which makes the whole world kin. The periods of depression 

 were wiped out. The curve of vitality no longer showed the 

 ominous recurrent depressions. At the same time the rate of 

 growth and division — that is to say, the physiological activity — 

 was increased by as much as 30 per cent. 



Something of the same effect is produced by strychnine, but 

 there is a remarkable and significant difference in the funda- 

 mental action of the two drugs, for whereas the beneficial effect 

 of alcohol endures after the drug ceases to be administered, 

 that of strychnine does not. Alcohol, as Calkin says, in spite 

 of the prodigiously increased rate of living, " exacts no physio- 

 logical usury," it is beneficial in its after effects. Strychnine is 

 harmful in its after effects ; the onset of decay and death is 

 hastened. 



What significance are we to attach to artificial rejuvenescence? 

 There are two possibilities. The chemical agent employed may 

 either add something which is missing or diminished in the 

 chemical make-up of the protoplasm, or it may restore a physical 

 state. The former implies that the chemistry of the growth 

 process is imperfect : the process of converting non-living to 

 living matter is subject to inaccuracies — inconceivably small 

 it is true, since they need to be magnified to the 170th 

 power of 2 before they destroy the working of the machine, 

 but cumulative from generation to generation. I incline to 

 think that senile decay is due not so much to such a chemical 

 insufficiency as to the wearing out of a physical state, of a 

 " potential." 



Consider a special case. Thirty minutes' immersion of an 

 individual Paramoecium in very dilute solution (1 part of salt in 

 1,000) of potassium phosphate was found to restore vitality, and 



