1895. NOTES AND COMMENTS. 227 



lines suggested in the mathematical section, but which at present is 

 considerably more advanced than the structure of the atom and of 

 ether. Incidentally Professor Meldola stated that he was preparing a 

 catalogue of the so-called organic substances that have been 

 synthesised. It seems that alcohol was the first organic substance 

 formed by chemists in the laboratory. At the time, however, it was 

 not recognised that alcohol was a substance really formed by the 

 agency of living things, and, consequently, the synthesis of it by 

 Henry Hennell, in 1826, attracted little attention. It was when 

 Wohler, in 1828, prepared urea from ammonium cyanate that the 

 current conceptions of organic chemistry were shaken, as urea 

 obviously was a product of the living animal. Even this synthesis, 

 however, may not be regarded as complete, for at that time ammonium 

 cyanate had not been prepared from inorganic elements. This, of 

 course, has now been done, and not only urea but a large number of 

 other substances have been built up in the laboratory from inorganic 

 elements. " From the time of Wohler and Hennell, the course of 

 discovery in this field has gone steadily on. The announcement of a 

 new synthesis has ceased to produce that excitement which it did in 

 the early days when the so-called ' organic ' compounds were regarded 

 as products of a special vital force. The interest among the 

 uninitiated now rises in proportion to the technical value of the 

 compound. The present list of 180 odd synthetical products 

 comprises, among the latest discoveries, gentisin, the colouring matter 

 of the gentian root [Gentiana lutea), and caffein." 



But Professor Meldola is not certain that it is an adequate idea 

 of synthesis to restrict the word to the building up of compounds from 

 lower substances. He doubts, for instance, and many physiologists 

 will agree with him, whether in the vital laboratory of the plant the 

 formation of compounds is often one of synthesis in the strict sense of 

 the word. Like Bunge, the great German physiological chemist, and 

 like many English physiologists, he insists on the part played by 

 protoplasm in all these processes. He suggests that the first stage to 

 be explained is the nature of assimilation, and hints that in many 

 cases assimilation may be the formation of a compound between 

 protoplasm or some of the proteids in protoplasm and the foreign 

 substance. The subsequent formation of the organic substances in 

 the cell might then be, not a true synthesis — a building up from low to 

 high, but the formation of a lower compound from the complicated 

 union of protoplasm with other bodies. And in this connection he 

 recalls Sachs' opinion that starch itself is the first visible formation in 

 the assimilating processes of the green cells. " The future develop- 

 ment of vital chemistry, however, rests with the chemist and 

 physiologist conjointly ; the isolation, identification, and analysis of 

 the products of vital activity, which has hitherto been the task of the 

 chemist, is only the preliminary work of physiological chemistry 

 leading up to chemical physiology." 



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