ORGANIC SUBSTRATA OF THE ANIMAL ORGANISM. 25 



mical points of view, from which we may consider the chemical 

 nature of these heterogeneous substances ; or, in fine, we must not 

 leave it to chance in zoo-chemistry, whether or not we examine a 

 chemical substance according to its occurrence in, or absence from 

 the animal organism. We must pay special attention to the place 

 occupied by each member of the group of chemical substances, 

 while the contiguous members and allied substances, that may not 

 have occurred in the same order in other animal bodies, must not 

 be disregarded. It would be illogical to regard the metamorphic 

 products of those animal matters that we have not hitherto been 

 able to detect in the excreta of animal bodies, as excluded from 

 zoo-chemistry, or at all events, as constituting only a less essen- 

 tial and more supplementary portion of the science. Zoo-chemistry 

 should not only embrace, according to the principles of pure 

 chemistry, all substances standing in a more or less intimate relation 

 to the matters actually found in animal bodies, but it should like- 

 wise make the fullest and most extended application of the various 

 propositions and theories by which general chemistry has at differ- 

 ent times been enriched. At the first glance it might appear as if 

 the physiological momentum were entirely lost in such a con- 

 ception of zoo -chemistry, but so far from this being the case, we 

 find that by such a method physiology is made to afford the 

 greatest aid. 



The physiological importance of a body is mainly dependent on 

 its chemical composition and quality. If this proposition be true, 

 the assertion that a chemical conception of animal substances must 

 likewise be a physiological one, can no longer be called in question. 

 The physiological capacities of the material substrata of animate 

 beings can be referred only to their chemical qualities, and no form 

 of physiology, that was not tinctured with sophisms of the spiritualist 

 school, could hold that a chemical substance should depose all its 

 integral properties in the animate body, to assume higher or more 

 spiritual capacities in the vital sphere. But while we would endea- 

 vour in the following pages to establish the principle of the purely 

 chemical arrangement of zoo-chemical substances, we at the same 

 time most fully award to physiology what is its due. A chemical 

 arrangement of animal substances must be in perfect accordance 

 with a physiological one ; while the latter would neither be rational, 

 correct, or in accordance with nature, if it were to associate 

 substances having different chemical qualities, and artificially 

 separate others of analogous chemical characters. Thus, it is self- 

 evident, that substances containing no nitrogen, as starch, sugar, 



