202 Notes, ill. 5. " • 



degree of unity. Still even in these some portions of the whole, when isolated, seem to 

 retain a certain small degree of sensibility, that is show the presence of a soul. Tortoises, 

 for example, can still move, when the .heart has been removed " {De Ju. et Sen. 2 ; 

 De Resp. 17, 4). , . 



3. Because heat, though, not the soul itself, is the necessary agent of the soul in all its ' 

 operations. Cf. iv: 10, Note 11 ; i. i, Note 13. • 



4. As all sanguineous animals, i.e. all vertebrates, are capable of locomotion, these 

 words might seem surplusage. But they are not so. For A. holds that the bilateral 

 symmetry of animals belongs to them primarily in virtue of their locomotor organs ; 

 and that the symmetrical disposition of these determines an imperfect degree of bilateral 

 symmetry in the organs of vegetative life. ,Cf. iii. 2, Note il. 



5. A.'s general notions on the subject of nutrition were much as follows. • Food, being 

 the material for the formation of the body, must contain the same substances as those of 

 which the body itself is composed {De G. et C. ii-. 8, 4); and therefore, as the body is 

 complex, so must th^ food be {De Sensu; 5, 30)." No one substance therefore forms a 

 sufficient food for any living thing. Even plants which seem to live on water really live 

 on water and earth, as farmers who use manure know. The most nutritive substances 

 are those which are sweet {De Sensu, 4, 14), and in all nutritive substances it is the sweet 

 element which is really nutritivef, though the sweetness may be disguised by the inter- 

 mixture of bitter, etc. , into the flavour. With sweet substances must be reckoned fat, . 

 which is nearly allied to them {De Longit. Vita, 5, il). 



The food masticated in the mouth, but not otherwise altered (ii. 3, Note 5)., reaches 

 the stomach, where it is concoctfed ; the heat for this purpose, which is not common heat 

 l^ a heat with special powers (ii. 6, Note 7), being supplied by the liver and spleen, 

 which are hot organs in close contiguity with the 'stomach {D. P. iii. 7, 10). .The solid 

 and indigestible portion passes off by the lower bowel, but the fluid portion, which alone 

 can be serviceable in nutrition (cf. ii. 2, Note 4), is absorbed- by the blood-vessels of the 

 stomach and intestine {D. /". iv. 4, 3 ; ii. 3, 11), over the surface of ivhich they are 

 spread like the roots of a plant. These blood-vessels open by very minute and invisible 

 pores into the intestine, pores like those in' jars of unbaked olay that let water filter 

 through {D. G. ii. 6, 19). The matter thus absorbed passes up to the heart; irf the 

 form of vapour \a.vaQv}i.iaTa.C), not as yet being blood, but only (ii. 4, Note il) an 

 imperfect serum Jlfx^'P) • In the heart and vessels {De Somno, 3, 3] it undergoes a second _ 

 ■ concoction, these being the hottest parts 'of the body, and by this second concoction 

 the serum is converted into blood {H. A. iii. 19, 9), the ultimate food of all the organs. 

 The amount of blood thus formed is extremely small, as compared with the original • 

 materials ; for were it not so, the body would grow to an enormous bulk {D. G. i. 18, 

 46). The blood when made passes from the heart by the vessels (arteries and veins 

 alike), being mingled with air inhaled by the lungs and thence conveyed to the heart 

 (iii. -6, Note 3), and is carried to all parts of the body. Each organ selects from the 

 common stock those materials which it requires. The nobler parts, such as the flesh 

 and the Organs of sense, take the choicer elements, while the inferior parts, a,s bones and 

 sinews, are fed on the inferior elements or leavii^gs (uiroAefju/xaTo) of the former (Z>. G. 

 ii. 6, 41). This nutrition of the parts goes on most actively at night {De Sainno, i, 15). 



Xhus every part of the blood that can be turned to account is utilised ; but such as 

 from its qualify is unfit for use, for instance any bitter substance, is excreted as bile, 

 urine, sweat, etc., in company' with the matter which results fromi the decay {avvrt\\i%) 

 of the parts themselves. 



Such surplus of nutritious matter as there may be, after all parts are satisfied) is either 



