NATURE OF THE COMPOUNDS 5 



which, without unduly straining the facts, there is reason for believing 

 to be present in the products resulting from vital synthesis, the 

 other condition for ensuring inclusion in this work being of course 

 that the complex has been synthesised in the laboratory. The question 

 whether the agent which reveals the presence of the complex is a mild 

 or a violent one is for the purposes of the present treatment con- 

 sidered only as of subordinate importance. 



The liberal extension of the term ' vital product ' thus claimed has, 

 it is hoped, been used judiciously, and not pushed to an unwarranted 

 degree. All that can be said is that in the present state of knowledge, 

 where so much doubt surrounds the chemical history of the antece- 

 dents of vital products, full advantage has been taken of this doubt on 

 behalf of this compilation. Should it be proved hereafter that any 

 particular compound is the result of secondary synthesis, and that its 

 atomic complex is not formed by the living organism, it can easily be 

 removed from the list. 



The importance of including every possible complex, whether it is 

 obviously present in the vital product or whether its presence is 

 inferred only, will be more fully recognised if it is pointed out 

 that the inferred existence of any particular group of atoms in the 

 molecule becomes converted into a demonstrated fact, when, as in 

 many of the cases recorded, the compound has been produced syn- 

 thetically from a generator which is known to contain the group in 

 question. A few examples will serve more fully to illustrate the nature 

 of the difficulties which have had to be met, and will furnish further 

 justification for the mode of treatment adopted : 



Furfural [126] has been found in the aqueous distillate from many 

 ethereal oils from plants as well as in some of the oils. It has been 

 detected also in certain fermented liquors, such as whisky, &c. It is 

 doubtful whether this compound is really a biochemical product, since 

 it may have been produced by the breaking down of more complex 

 antecedents (pentoses, &c.) during the process of distillation. This 

 question has been much discussed of late by technical chemists, and 

 the balance of opinion is against its being a product of alcoholic 

 fermentation. Nevertheless this aldehyde has been included because 

 it may be fairly said that the complex of atoms which so easily closes 

 up with the formation of this heterocyclic molecule pre-exists in the 

 vital compound or compounds which are its generators. Should any 

 of these generators be hereafter synthesised it is possible that furfural 

 may be made use of in their synthesis. 



Again, orcinol [75] has not yet been found in the free state in any 

 plant, but many complex acids found in lichens yield this phenol with 

 varying degrees of facility, from simply boiling with water, alkaline 

 carbonates, or baryta water, to fusion with caustic alkali. It is there- 

 fore evident that the orcinol complex is contained in these lichen acids, 

 and should any of these compounds ever be synthesised it is certain 



