J32 LIFE : OUTLINES OF GENERAL BIOLOGY 



goes on in non-living Nature and what goes on in the living body. 

 It was at a stroke the death-blow to the doctrine that organic 

 substances could not be made except by organisms; and it was the 

 beginning of that brilliant succession of synthetic achievements 

 which have yielded not only sugars and alcohols, but such complex 

 compounds as salicylic acid, indigo, madder, amino-acids, adrenalin, 

 and thyroxin. The s}Tithetic chemist is drawing near to the artificial 

 production of proteins — hammering at the gates of Life's citadel. 

 Hut apart from the synthetic triumphs which followed, and still 

 follow, Wohler's unsensational step, there was the blazing of a new 

 trail. The products and processes of the living body were no longer 

 a preserve for the physiologist, they were recognised as amenable 

 to chemical analysis. It was on a stage beyond Lavoisier's the 

 beginning of biochemistry. 



Another great initiator was Pasteur, chemist more than biologist, 

 who advanced logically from his study of tartrates, not only to a 

 recognition of the manifold activities of bacteria, but to some pre- 

 vision of the part that ferments or enzymes play in vital processes. 

 It is a commonplace now that we cannot understand either the 

 rapidity or the relative tirelessness of metabolism unless we take 

 account of the ceaseless fermentations. 



But while we cannot but look upon Pasteur as a great initiator, 

 profoundly influencing biology, we would not dwell on this, since 

 the study of ferments began with an investigation of fermenting 

 organisms, like the yeast-plant, and the transference of attention to 

 non-living enzymes came later. It might fairly be said, we think, 

 that in connection with ferments biology was at first in the service 

 of chemistry, rather than the other way round. Moreover, bacteri- 

 ology is an inseparable field of biology. 



Our treatment must be simply illustrative; and as instances of 

 the indispensability of chemistry to biology we would select (a) the 

 study of the photosynthesis that goes on in every sunlit green leaf, 

 and {b) the study of the properties of matter in a colloidal state. 

 The late Sir William Bayliss spoke of the action of chlorophyll as 

 "perhaps the most interesting of all natural phenomena"; and he 

 might have added what he meant, that the photosynthesis brought 

 about in the green leaf is the most important process in the living 

 world. It produces the food on which all animals and mankind 

 ultimately dejx^nd; and it has made and continues to make the 

 oxygen we breathe. Now the study of the fundamental work of the 

 green leaf began among the chemists, and it is still continuing 

 among the chemists. Recall the early steps, how Priestk y showed 

 (1774) that air "spoilt" by mice is made good again by sprigs of 

 green mint; how Ingenhousz showed (1780) that the sunlight is 

 necessary for the liberation of "dephlogisticated air", afterwards 

 called oxygen ; and how Senebier showed (1783) that what occurs is 



