October 20, 192 1] 



NATURE 



243 



The Laboratory of the Living Organism.^ 

 By Dr. M. O. Forster, F.R.S. 



TV/f AXV and various are the reasons which 

 ^^ ^ have been urged, at different periods of its 

 history, for stimulating the study of chemistry. 

 In recent years these have been either defensive 

 or frankly utilitarian, in the latter feature recall- 

 ing the less philosophic aspects of alchemy ; more- 

 over, it is to be feared that a substantial propor- 

 tion of those who have lately hastened to prepare 

 themselves for a chemical career have been actu- 

 ated by this inducement. It is the duty, there- 

 fore, of those who speak with any degree of ex- 

 perience to declare that the only motive for 

 pursuing chemistry which promises anything but 

 profound disappointment is an affection for the 

 subject sufficiently absorbing to displace the attrac- 

 tion of other pursuits. Even to the young 

 chemist who embarks under this inspiration the 

 prospect of success as recognised bv the world is 

 indeed slender, but, as his knowledge grows and 

 the consequent appreciation of our ignorance 

 widens, enthusFasm for the beauty and mystery 

 of surrounding nature goes far in compensating 

 for the disadvantages of his position, Not only do 

 chemical principles underlie the operations of 

 every industry, but every human being — indeed, 

 every living plant and animal — is, during each 

 moment of healthy life, a practical organic 

 and physical chemist, conducting analytical and 

 synthetical processes of the most complex order 

 with imperturbable serenity. Xo other branch of 

 knowledge can appeal for attention on comparable 

 grounds ; and without suggesting that we should 

 all, individually, acquire sulficient chemical under- 

 standing fully to apprehend the changes which 

 our bodies effect so punctually and so precisely — 

 for this remains beyond the power of trained 

 chemists — it may be claimed that an acquaintance 

 with the general outlines of chemistry would add 

 to the mental equipment of our people a source 

 of abundant intellectual pleasure which is now 

 unfairly denied them. In following the customary 

 practice of surveying matters of interest which 

 have risen from our recent studies, therefore, it 

 is the purpose of this address to emphasise also 

 those aesthetic aspects of chemistry which offer 

 ample justification for the labour which its pursuit 

 involves. 



What is breakfast to the average man? A 

 hurried compromise between hunger and the news- 

 paper. How does the chemist regard it? As a 

 daily miracle which gains, rather than loses, fresh- 

 ness as the years proceed. For just think what 

 happens. Before we reach the table frizzled 

 bacon, contemplated or smelt, has actuated a 

 \vonderful chemical process in our bodies. The 

 work of Pavlov has shown that if the dog has 

 been accustomed to feed from a familiar bowl the 

 sight of that bowl, even empty, liberates from the 



1 Abridged from the presidential address delivered to Section B 

 (Chemistry) of the British Assoriation at Edinburjh on September 8. 



NO. 2712, VOL. loS] 



appropriate glands a saliva having the same 

 chemical composition as that produced by snuffing 

 the food. This mouth-watering process, an early 

 experience of childhood, is known to the polite 

 physiologist as a "psychic reflex," and the vari- 

 ous forms assumed by psychic reflex, responding 

 to the various excitations which arise in the daily 

 life of a human being, must be regarded by the 

 chemical philosopher as a series of demonstrations 

 akin to those which he makes in the laboratory, 

 but hopelessly inimitable with his present mental 

 and material resources. For, extending this prin- 

 ciple to the other chemical substances poured suc- 

 cessively into the digestive tract, we have to 

 recognise that the minute cells of which our 

 bodies are co-ordinated assemblages possess and 

 exercise a power of synthetic achievement con- 

 trasted with which the classical syntheses, occa- 

 sionally enticing the modern organic chemist to 

 outbursts of pride, are little more than hesitating 

 preliminaries. Such products of the laboratory, 

 elegant as they appear to us, represent only the 

 fringe of this vast and absorbing subject. Carbo- 

 hydrates, alkaloids, glucosides, and purines, com- 

 plex as they seem when viewed from the plane of 

 their constituent elements, are but the molecular 

 debris strewing the path of enzyme action 

 and photochemical synthesis, whilst the en- 

 zymes produced in the cells, and applied by 

 them in their ceaseless metamorphoses, are so 

 far from having been synthesised by the 

 chemist as to have not even yet been 

 isolated in purified form, although their specific 

 actions may be studied in the tissue-extracts con- 

 taining them. 



Reflect for a moment on the specific actions. 

 The starch in our toast and porridge, the fat in 

 our butter, the proteins in our bacon, all insoluble 

 in water, bv transformations otherwise unattain- 

 able in the laboratory are smoothly and rapidly 

 rendered transmissible to the blood, which accepts 

 the products of their disintegration with military 

 precision. Even more amazing are the conse- 

 quences. Remarkable as the foregoing analyses 

 must appear, we can dimly follow their progress 

 bv comparison with those more violent disruptions 

 of similar materials revealed to us by laboratory 

 practice, enabling such masters of our craft as 

 Emil Fischer to isolate the resultant individuals. 

 Concurrently with such analyses, however, there 

 proceed syntheses which we can scarcely visualise, 

 much less imitate. The perpetual elaboration of 

 fatty acids from carbohydrates, of proteins from 

 amino-acids, of zymogens and hormones as prac- 

 tised by the living body are beyond the present 

 comprehension of the biochemist ; but their re- 

 cognition is his delight, and the hope of ulti- 

 mately realising such marvels provides the 

 dazzling goal towards which his efforts are 

 directed. 



