94 Dk. Mitchell «n the Occurrence of Suf/ar in the Animal Economy. 



those supplied by the vegetable kingdom, for we have found them both 

 fonning and destroying sugar. 



It does not follow, that because the animal organism seems thus to 

 possess transforming powers, which we cannot command in the laboratory, 

 that chemistry is to be dismissed from the study of the phenomena of life. 

 On the contrary, I believe that it alone can, in many cases, remove the 

 difficulties which arrest the progress of physiology ; but I am also of 

 opinion that, in order to the successful prosecution of such investigations, 

 they must enter the field and work conjointly. The saliva, &c. possess the 

 power of converting starch into sugar without any reference to whether 

 chemists know or are ignorant of their having such properties ; and 

 although we have not yet discovered them, many other catalytic influences 

 may be eflecting their transformations in the organism, and amongst them 

 may be one capable of converting the oleaginous into saccharine and 

 and albuminous matters. 



The simplest conception of the saccharine principle is an association of 

 water and carbon, and in this light it may be regarded as the interme- 

 diate link between inorganized and organized matter. This union of 

 water and carbon, and the consequent formation of the saccharine prin- 

 ciple is efTected by the lowest vital agency with which we are acquainted 

 — that of plants. It may occur, as Prout believes, from a direct union 

 between these substances ; but it seems to take place most usually by the 

 aid of a collateral extrication of oxygen, during which the unfettered 

 carbon is appropriated. When this association is simple, starch or sugar 

 is the result ; but when more complicated, and nitrogen, phosphorus, and 

 sulphur arc involved, various compounds are produced, which differ in 

 their properties between sugar and albumen. 



It has not yet been shown, whether the vital energies of plants can 

 convert oleaginous into saccharine and albuminous matters ; but the vital 

 organs both of plants and animals appear capable of performing the 

 reverse act, that of changing saccharine into oleaginous matters, and this 

 is probably the usual mode in which oils are formed in plants and animals. 



The union of water with carbon, and afterwards with nitrogen, has 

 been maintained to be the peculiar function of plants. There seems 

 reason for believing, however, that it is not limited to them. Prout, who 

 holds this opinion, gives this singular paragraph, written more from an 

 apprehension of what he felt would eventually be discovered, than from 

 what he himself knew at the time : — 



" In all animals there is a vegetative organ, (if we may be allowed the 

 expression,) capable in a greater or less degree of performing the same 

 functions as vegetables, i.e. of comblnuig water with carbon; or, if not 

 beginning at this low point of the scale, at least of combining the organized 

 saccharine principle with azote, &c. so as to form albuminous products. 

 This vegetative organ is the liver; and though the vegetative faculty 

 alluded to appears to exist in the livers of different animals in very different 

 degrees, yet in no instance is it entirely wanting. In all the more perfect, 



