252 NUTRITION. 



" This is referable both to the laws of affinity " and repulsion, 

 " by the former of which we imagine particles attract and, as it 

 were, appropriate others which are similar and related to them- 

 selves," while by the latter others are cast off; and to the peculiar 

 powers of life which only can effect " the proper application of 

 shapeless elementary matter, and its modification to particular 

 forms." The blood contains either the principles themselves of 

 various solids, or principles readily converted into them by chemi- 

 cal change. For instance, we know how readily a portion of it 

 grows solid out of the body; and the albumen of the egg is at 

 first almost entirely fluid, but gradually a portion of it becomes 

 insoluble 1 "; we see mucus expectorated sometimes of great con- 

 sistence, though it must have been poured forth fluid. Farther, 

 the fluids of the egg, after the influence of the fluid of the male, 

 solidify by themselves, and at length form an animal. A coagulum 

 of blood will of itself become vascular, and be converted into an 

 organized solid. Such are facts of formation, and we can have 

 less difficulty in conceiving that the fluids brought into proximity 

 with solids unite with them in the case of nutrition. We know also 

 that gelatine enters into the composition of every part, and that the 

 skin is little else, whereas the blood contains none : but then gela- 

 tine differs from albumen, in only containing three or four per cent, 

 less carbon, and carbon is thrown off from the body incessantly. 



" The union of both these powers, we conceive, must be the 

 source of the nutrition of such similar parts as are not supplied 

 with blood itself, but are, nevertheless, at first, generated by a 

 most powerful arid infallible nisus, grow, are nourished throughout 

 life, and, if destroyed by accident, are very easily reproduced. s 



" As this appears to be the true account of nutrition in general, 

 so, on the other hand, this function evidently has great varieties of 

 degree and kind," generally and locally, " especially where, from 

 the more or less lax apposition of the nutritious matter, the struc- 

 ture of the similar parts is more or less dense, and the specific 

 weight of the whole body more or less considerable. 1 In this 



r M. Raspail, 1. c. p. 1 94. 



s " Zwo Abhandlungen iiber die Nutritionskraft welche von der Acad. der Wiss. 

 in St. Petersburg den Preiss getheilt erhalten haben. Petersburg. 1789. 4to. 



De Grimaud, Memoire surla nutrition quia obtenu\Vnccessit. Ib. same year. 4to. 



Steph. J. P. Housset, on the same subject (in the same school) in his Memoires 

 physiologiques et d'hist. naturelle. Auxerre. 1787. 8vo. t. i. p. 98." 



' J. Robertson, On the specific Gravity of living Men. PM. Trans, vol. 1. 

 P. i. p. SO. sq. 



