i62 . * Noks. ii. 4. 



(iv. 5, Note 20). Those that change colour are the cephalopods (iv. 5, Note 15); 

 but the sanguineous chamaeleon does so as well (iv. Ii, Note 28). 



6. Though from some of A.'s language it might be supposed that he looked on the 

 whole blood as being fluid while in the living body, and so anticipated Borelli,' this 

 passage shows that he really considered the fibrine to exist in the solid form even during 

 life; as also did Plato «(y^w//'j- Tr. ii. 578). 



7. The hot vapour-bath to which A. alludes was made by getting under an air-tight 

 cloth and throwing aromatic substaiices upon hot embers. Cf. Herodot. iv. 75. 



8. Elsewhere \H. A. iii. 19,' 6) the ass is instanced as well as the bull. Bovine 

 animals (but still more swine and horsps) have a larger proportion of fibrine in their 

 blood than man {Andral, Ann. du Chimie, 1842, p. 306); and from such scanty • 

 observations as exist it would seem that the blood of bulls is richer in fibrine than that 

 of cows or oxen {ibid. p. 307). Thackrah seems 'to have arrived at much the same 

 general conclusion as Aristotle. " Although my experiments are far from e^'ipcing a 

 disparity uniform in its reference to the classes' of animals,, yet it appears probable that 

 a more complete examination would prove the crassamentum to bear a proportion to tl.ie 

 strength and ferocity of the animal, since I never found the serum in such quantity as in 

 the timid sheep, nor the crassamentum so abundant as in the predatory dog" {On the 

 Blood, 1834, p. 154). . 



That abundant fibrine goes with strength and ferocity appears to be a popularly 



accepted notion. . . ' . 



" Come you spirits 



That tendon mortal thoughts, unsex me here 



And fill me from the crown to the toe, tqp-full 



Of direst cruelty ! * Make thick my blood. "■ — Macbeth, i. 5. 



9. I cannot find any exact observations as to the period of coagulation of bull's blood- 

 It differs in composition from that of the ox (see last note) and may therefore differ 

 from it in this point also. The blood of an ox, however, commenced coagulating, in 

 Thackrah's experiments, on an average in 6 minutes ; the minimum being 2 and the 

 maximum 10 ; whereas that of the sheep, hog, and rabbit commenced in from ^ to 2 

 minutes; that of a duck in from i to 2 minutes; and that of a mouse, according. to 

 Haller, "in a moment." Thackrah says {On the Blood, p. 154) that "from my 

 observations the general inference may be drawn that coagulation commences sooner in 

 small and weak animals than in large and strong." This seems in contradiction with 

 A. 's statement. 



10. Cf. Meteor, iv. ch. 6, 7, 8, where A. discusses at length the questions of coagula- 

 tion, liquefaction, etc. "Compounds of earth 'and water," he says, "such, for instance, 

 as blood, in order that they may retain their fluid condition, require a certain amount 

 of water and a certain amount of heat. They can therefore be solidified either by 

 excessive heat or by CQld. By heat because it directly causes evaporation 6f the water. 

 By cold because in the first place it expels the heat, and secondly because the heat in 

 passing off carries with it much of the water in the shape of vapour. Blood when 

 withdrawn from the warm body and exposed to the cold air coagulates owing to tfie 

 second cause." . ' ' ■ 



11. A*, considers the fibrine, or rather the clot, i.e. the -fibrine with the corpuscles, to be 

 the part of the blood which is ready to serve for nutrition. Besides this, he says, there 

 are in the serum materials derived, from the food which after concoction will be converted 

 into this nutritious form (so also' Z;^. A. iii. 19, 9— 12), and others again whiph are 

 derived from the waste of the body. This accords with the view of those who hold that 



