CHAPTEE IX. 

 AEISTOTLE'S HOMCEOMEEIA. 



The homoeomeria are described chiefly in H. A. iii. cc. 

 2-17 and P. ^. ii. cc. 1-9. It has been said that these parts 

 of Aristotle's works bear some relationship to the science of 

 Histology, but this is true only in a very limited degree. 

 The science of Histology, in fact, cannot be said to have 

 existed until Malpighi, Leeuwenhoek, and other investi- 

 gators successfully used the microscope in the seventeenth 

 century. How very slight the relationship is between 

 Aristotle's work on the homoeomeria and the science of 

 Histology will be seen from the following descriptions of his 

 common homoeomeria, commencing with those included by 

 him amongst the solid or dry and passing on to those 

 included among the soft or liquid homoeomeria. The 

 former include bone, cartilage, sinew, " fibre " and the like, 

 the material forming blood-vessels, skin and membrane, and 

 the latter include flesh, suet and fat, marrow, blood, serum 

 and the like, and milk. 



1. Bone and Cartilage. — Aristotle says that the bones 

 of viviparous quadrupeds with blood do not differ much in 

 themselves, but merely in their relative degrees of hardness 

 and softness, strength and weakness, and in the presence or 

 absence of marrow.* He considered ordinary bone to 

 contain more earthy matter than the bone found in fishes 

 and, in H. A. iii. c. 7, s. 6, he says that the dolphin has 

 ordinary bones and not bones like those of fishes, which are 

 only analogous to ordinary bones. 



He refers particularly to the hardness of the bones of 

 lions, and says that they are harder than the bones of other 

 animals, for, when struck together, sparks fly just as if the 

 bones were stones, f It is true that many of the bones of 

 lions are very hard. According to Owen, they contain 

 72"3 per cent, of inorganic constituents, or more than three 



-■■■ H. A. iii. c. 7. s. 5 ; P. A. ii. c. 9, 655a. 

 f H. A. iii. c. 7, s. 6 ; P. A. ii. c. 9, 655a. 



