ARISTOTLE'S HOMCEOMERIA. 109 



what these were intended to be, and he has often been mis- 

 judged through a careless or mistaken translation of these 

 words. Considered as homoeomeria, neuron refers chiefly to 

 the material of which sinews, tendons, and ligaments are 

 made, and is to the material of the fibrin of the blood, the 

 fibre-like vessels containing a colourless fluid in many of the 

 lower animals, and various fibre-like structures, such as 

 small branches of the nervous system, and the connective 

 tissues extending through the flesh. 



Aristotle says that sinew is fissile longitudinally but not 

 transversely, that it is very extensible, and that, when 

 severed, it does not re-unite.* He also says that the fluid 

 about the sinews is mucous, white, and gelatinous, and that 

 the sinews are nourished by this fluid and seem to be pro- 

 duced from it.t 



In the passages from Hippocrates, already referred to, it 

 is stated that sinew does not re-unite after it has been cut. I 

 It is probable that Aristotle copied this from Hippocrates. 

 Plato's statements about sinews differ greatly from Aristotle's. 

 He says that they are firmer and more glutinous than flesh, 

 but softer and moister than bone, and that they are yellow 

 and compounded in some way of bone and imperfectly 

 formed flesh. § 



Aristotle's statement concerning the fluid about the 

 sinews is incorrect. The chief function of the synovial 

 fluid is to lubricate the joints, and the fluid itself is probably a 

 secretion, but may be, in part at least, a product of the 

 frictional action between the surfaces of the joints. 



The view sometimes expressed that Aristotle's neura 

 were nerves will be discussed in Chapter xii. 



Aristotle does not give any information of importance 

 about the properties of his " fibres," excepting those which 

 he believed were in the blood. These "fibres" will be 

 more conveniently dealt with in the part of this chapter 

 relating to the blood. 



3. Material forming the Blood-vessels. — Aristotle mis- 

 understood the nature of this material, for he considered 

 what are now called the venae cavse, and probably some 

 other veins, to be made up of skin and membrane, and the 

 aorta to be very sinewy and its small branches to be quite 

 sinewy. II 



■■' H. A. iii. c. 5, s. 3. f Ibid. 



I Aphorisms, Section 6, § 19 and Section 7, § 28. 



§ Timceus, 14,. \\ H. A. iii. c. 3, s. 3. 



