in its Relations to Physiology. 431 



How strange it is that chemistry should have to fight a kind of battle 

 in order to be permitted to render that assistance it can well afford to 

 physiology, to extend and to augment, to make more precise and definite 

 the significations of physiological terms and to correct the conception 

 and definition of organic substances, their origin, properties, and re- 

 lations ! 



It canot be disputed that a simple substitution of the formula of caseine 

 for the word caseine, of the formula of cellular substance for the word 

 cell, of the formulae of bile, uric acid, &c, renders at once intelligible 

 a number of relations which, without the formulae, would be im- 

 perceptible, or, at least, in the greatest degree obscure. When the 

 formula of caseine, compared with that of blood, tells us that caseine 

 is identical in composition with the principal constituents of the blood, 

 does not these bring us far nearer to the apprehension of its origin 

 from the blood and its transformation into blood than we were before ? 

 A comparison of the formulae of the constituents of the blood and of cel- 

 lular substance points out to us how much oxygen must join, and how 

 much carbon must separate from albumen or fibrine to convert these 

 substances into cellular tissue ; and if urea and uric acid are products of 

 the transformation of living tissues, and ultimately of blood, does not 

 the formula of urea and that of uric acid afford us a perfectly exact 

 measure for the quantity of organic substance which has undergone 

 this transformation? The formulae speak for themselves, but what 

 they tell us no longer belongs to chemistry, it now becomes a part of 

 physiology. 



I admit that the accurate determination of the composition and pro- 

 portions of these bodies, and the assigning their numbers, appertains 

 to the domain of chemistry, and may be called chemistry, but the ap- 

 plication of the discoveries of organic chemistry to a more comprehen- 

 sive and correct definition of the physiological conception, and to the 

 more extensive apprehension of the properties, relations, and formations 

 of these organic substances, belongs to chemistry only de nomine. 



The production of iron from its ores is a metallurgic process, but the 

 application of iron after it is produced to the manufacture of needles 

 and innumerable purposes in the arts belongs not to metallurgy. 



It is the same with respect to the methods of the chemist ; it is only 

 by mistake they are called exclusively chemical methods ; they are 

 methods in accordance with plain common sense and sound reason, and 

 therefore are applicable everywhere and in all sciences. 



The mineralogist is no longer misled by the infinitely various forms 

 under which calcareous spar is found in nature ; he is now, by the dis- 



S K 



