HISTORICAL 3 



be fully borne out by the critical examination of the papers referred 

 to, and this conclusion has recently been upheld by Fritzsche, who 

 also points out that these results were known to contemporary Con- 

 tinental chemists \ 



II. NATURE OF THE COMPOUNDS REGISTERED AS 

 VITAL PRODUCTS 



The term 'vital product' has been adopted in preference to the 

 designation ' natural product,' which first suggested itself because the 

 latter, strictly interpreted, includes also mineral or inorganic com- 

 pounds. In working out the details presented in the following pages 

 much consideration has had to be given to the question as to which 

 compounds should be regarded as of vital origin. In works dealing 

 with organic or physiological chemistry it is generally stated or implied 

 that such compounds are formed by the living plant or animal, as the 

 result of the physiological activities of its various organs or tissues. 

 It is also understood, in accordance with modern views, that the seat of 

 such physiological activity is the cell. AJthough this conception of the 

 nature of a vital product at first sight appears to bring the term within 

 easily definable limits, it soon became evident when the individual 

 products came under consideration that from the chemical point of 

 view, apart from the question of the physiological mechanism by which 

 the compounds are formed, some more precise understanding would 

 have to be arrived at. Thus in many cases it is necessary to register 

 a vital product not under one heading as a simple molecule, but under 

 two or more headings if the compound is obviously built up of, and is 

 easily resolvable into, two or more compounds of less molecular com- 

 plexity. 



By way of illustration, it is doubtful whether either methyl alcohol 

 or salicylic acid occurs in nature in the free state ; but the ester, 

 methyl salicylate, is the chief constituent of the oil of wintergreen 

 (Gaultheria), and is contained in the ethereal oils of large numbers of 

 other plants. It is further probable that methyl salicylate does not 

 itself exist in the plants in the free state, but in the form of a glucoside, 

 gaultherin. The glucoside is therefore, strictly speaking, alone entitled 

 to registration. Similarly with respect to alizarin, which does not 

 exist as such in the plant, but in the form of the glucoside ruberythric 

 acid. In cases such as these, which are typical of a large class, the 

 product has been regarded as having been synthesised, and compounds 

 such as methyl alcohol, salicylic acid, and alizarin have been regarded 



1 Journ. pr. Ch. [2] 65, 597. The references to ' PoggendorfTs Annalen' given are 9, 21 ; 

 14, 282. The latter, which relates to HennelFs second paper, is given also in Beilstein's 

 ' Handbuch,' Vol. I, p. 222, but, strangely enough, has been corrected in the Supplement 

 (Vol. I, p. 72) so as to make it appear as though M. Berthelot's reclamation had been 

 admitted. 



B2 



