i] CHEMICAL EMBRYOLOGY 27 



Haldane was not convincing in his criticism of Driesch, and there 

 can be little doubt that Driesch's position is a perfectly tenable one, 

 provided its supporter closes his eyes to the nature of the scientific 

 method on the one hand, and the actual history of recent scientific 

 progress on the other. Another side of Haldane's teaching was the 

 view that the living animal was in some way less abstract than the 

 world of physics ; physics and biology, he thought, might some day 

 coalesce, but it would then be found that physics would not have 

 swallowed up biology; rather the contrary would occur and biology 

 would swallow up physics. "The idea of life", he said, "is nearer 

 to reality than the ideas of matter and energy, and therefore the 

 presupposition of ideal biology is that inorganic can ultimately be 

 resolved into organic phenomena, and that the physical world is thus 

 only the appearance of a deeper reality which is as yet hidden from 

 our distinct vision and can only be seen dimly with the eye of scien- 

 tific faith." 



There had been precursory voices of all this in the nineteenth 

 century, as when, in spite of the discoveries of Cagniard de Latour 

 and others that the yeast-cell played an essential part in fermenta- 

 tion, Justus von Liebig refused to credit them, fearing that their 

 suggestions were a return to explanations by vital force. "Chemical 

 actions may very well explain physiological actions, but certainly 

 not vice versa ", said Moritz Traube. Claude Bernard, moreover, dis- 

 cussed the matter with his usual subtlety. "Physiologists", he said, 

 "must not forget that a living being is an organism with its own 

 individuality. Since physicists and chemists cannot take their stand 

 outside the universe they study bodies and phenomena in themselves 

 and separately without necessarily having to connect them with 

 nature as a whole. Physiologists, on the contrary, find themselves 

 outside the animal organism which they see as a whole, even when 

 trying to get inside so as to understand the mechanism of every part. 

 The result is that physicists and chemists reject all idea of final causes 

 for the facts which they observe while physiologists are inclined to 

 acknowledge an harmonious and pre-established unity in an organised 

 body, all of whose actions are independent and mutually generative. 

 If we break up an organism for the sake of studying its parts it is only 

 for the sake of ease in experimental analysis, and by no means in 

 order to conceive them separately. Indeed, when we wish to ascribe 

 to a physiological quality its value and true significance we must 



