Notes, iii. 4 — 5. 201 



passage that the heart is riot liable to disease, or at any rate less liable than other organs ; 

 just as Galen said that it was made of hard fle.sh which could not easily be injured. 

 But in fact A. says nothing of the kind, but merely states what is fairly true, viz. that 

 diseases of the heart are more certainly fatal, and less consistent with apparently good 

 health, than diseases of other parts; so that when a victim, i.e. an animal supposed to be 

 of sound health, is sacrificed, its heart is never found diseased, though such is frequently 

 the case when an animal djes of a malady. What would A. have thought of the bull 

 sacrificed by Caesar, which the soothsayers asserted to have no heart at all! {Cicero, 

 De Div. ii. i6). ' • . 



38. The spleen is liable to tubercle, and is indeed, with the lymphatic glands, its 

 favourite seat in children {Rokitansky).' If is also extremely liable to embolism; and 

 enlarges in malarious diseases, which were probably very common in A. 's time and 

 country. 



(Ch. 5.) 1. Cf. iii. 4, Note 24. It is strange that even up to the present day it 

 should be universally stated by writers on the history of physiology that up to the time 

 of Galen all philosophers supposed that the arteries contained nothing but air. Even 

 Cuvier, the great admirer of Aristotle, attributes to him this erroneous notion. Milne 

 Edwards actually considers why it was that Galen attacked Erasistratus rather than 

 Aristotle for holding this doctrine. Nothing can be plainer than that A. knew perfectly 

 well that the arteries contained blood, and this chapter is sufficient by itself to show that 

 he did so. The mistake has, I imagine, arisen, from two causes. Firstly, that writers 

 have got into confusion by translating ^\€i|( into vein ; Whereas it nxeans blood-vessel, ih.z.\. 

 is artery or vein alike ; and by still more absurdly translating ipr-fipia into artery, 

 whereas it means trachea. Secondly, that the treatise De Spiritu has been trusted, 4^ 

 a. genuine work of Aristotle ; whereas it is shown not only by its language but by its 

 statements to be most certainly spurious, and is in flagrant contradiction with the 

 genuine treatises. Cf. ii. i6, Note ii. 



2. Cf. iv. 5, Note 71. Alluding to such Invertebrata as insects, myriapods, and 

 annelids, which he frequently mentions as capable of living for a short time when cut 

 into segments ; which shoWs that each segment must have its own centre of animality ; 

 the entire animal seemingly consisting of an aggregation of many animals, each with 

 a certain individuality, which ordinarily is merged in the life of the aggregate, but is 

 capable of asserting its existence \yhen the segment is isolated ; the only reason, in fact, 

 why such an isolated segment does not live more than a, short time, being that it has not 

 got the necessary organs of nutrition. One cannot but be struck with the similarity of 

 this view to that set forth by Herbert Spencer {Princ. of Biol. ii. ch. 4 and 5), who 

 considers the Articulata to be "tertiary aggregates." The following passage expresses 

 A.'s view: "Many insects oanlive when cut into pieces, in this respect resembling 

 plants. This necessarily implies that their nutritive soul, though actually one, is 

 potentially many ; and, in the case of the animals, the same must be true of the 

 sensory soul ; for each segment plainly retains some- sensibility. Such an animal resembles 

 a number of separate animals united by growth into a single mass. There is this 

 difference between such an animal and a plant. The segments of a plant can live 

 for in indefinite time, and each segment can grow into the form of the entire plant 

 of which it was a portion. But . the segments of the animal only live for a very 

 short time. This is because they have not got the organs that are necessary for their 

 maintenance, some of the segments having no mouth, some no stomach, some neither 

 mouth nor stomach, and so on. In animals of the most perfect conformation, no such 

 phenomena as these are observable ; because their nature has reached the highest possible 



