OF NUTRITION. 281 



propriate others which are similar and related to them- 

 selves ; and to the nisus formativus, which we shall 

 enlarge upon hereafter, and to which the proper appli- 

 cation of shapeless elementary matter and its modifi- 

 cation to particular forms, must be ascribed. 



464. 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, but are, never- 

 theless, at first generated by a most powerful and in- 

 fallible nisus, grow, are nourished, and, if destroyed 

 by accident, are very easily reproduced ;* such are the 

 nails, hairs, &c. 



465. As this appears to be the true account of nutri- 

 tion in general, so, on the other hand, it evidently has 

 great varieties of degree and kind, especially where, 

 from the more or less lax apposition of the nutritious 

 matter, the structure of the similar parts is more or 

 less dense, and the specific weight of the whole body 

 more or less considerable.f In this respect, not only 

 individuals, but whole nations, differ from each other. 

 The Yakuts and Burats, who are remarkable for the 

 lightness of their bodies, are a sufficient example of 

 this. 



* Zwo Abhandlungen uber die Nutritionskraft welche von der Acad, der 

 WUs. in St. Petersburg den Preiss getheilt erhalten haben. Petersburg. 

 1789. 4to. 



De Grimaud, Mini, sur la nutrition qui a obtenu Faccessit. lb. same year. 4to. 



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

 ohysiologiques et d'hist. naturelle. Auxerre. 1787. 8vo. T. i. page 98. 



t J. Robertson, On the specific gravity of living men. Philos. Trans. Vol. L. 

 t\ i. page 30 sq. 



