in its Relations to Physiology. 439 



advancement of science in their publications than for the extension of 

 their own reputation for sagacity and penetration ; whilst many a can- 

 didate for practice, pressed by his pecuniary necessities, writes a book 

 as the best means of advertising himself; and to impose thus upjm the 

 public requires so very little labour or skill, that we may almost won- 

 der that such works are not still more numerous. 



In chemico-physiological works, physiology is threatened with dan- 

 ger, not from chemists, but from physiologists themselves and phy- 

 sicians. 



It is not chemistry which asserts that peroxide of iron and protoxide 

 of iron perform a part in the respiratory process ; this assertion is made 

 by physicians. 



Chemistry knows but one organic compound, which invariably con- 

 tains iron as a constituent. It is not a chemist who considers proteine 

 the basis of blood and the tissues, but it is the iatro-chemist, who has 

 introduced into the vital process the idea of the organic radicals. The 

 chemist has not done so, because he knows that acetic acid may be 

 derived from wood, and in its anhydrous state has the same composi- 

 tion as wood, and because he knows that acetic acid may be derived in 

 the same manner from a thousand other substances, without being (on 

 that account) the prototype of their constitution. 



The iatro-chemist knows a proteine tritoxide, and deutoxide, he de- 

 termines the atomic weights of fibrine, albumen, and caseine from their 

 combinations with hydrochloric acid and peroxide of lead. It is he who 

 wishes to establish the absolute number of atoms composing the ele- 

 ments of proteine, who disputes about the formula ; this is the iatro- 

 chemistry of the present time. 



It is iatro- chemistry which proposes to make the addition of an atom 

 of oxygen to lung tubercle render intelligible the formations of liver 

 tubercle, which is just as clear as to suppose the addition of oxygen to 

 ear-wax in an ear-spoon (cochlea), to make spiritus cochlearia. 



I am perfectly aware that I bear the blame of many of these deduc- 

 tions, which I do not hesitate utterly to repudiate. 



Iatro-chemistry, not chemistry, pretends to prove from the composi- 

 tions of mould which forms in a solution of the sugar, that plants 

 derive their nitrogen from the gaseous nitrogen of the atmosphere ; for 

 chemistry knows that pure solution of sugar does not admit the forma- 

 tion of any mould whatever. Chemistry knows that the so fabulously 

 powerful vital principle is incapable of employing any element as the 

 constituent of an organism. Chemistry knows that it is not diamond 



which nourishes the organism, but a carbon compound ; not hydrogen, 



3 L 



