GENERATION OF ANIMALS, II. vi. 



the essence " ; but as soon as we begin to deal with 

 those things that come into being through a process 

 of formation, we find there are several first principles 

 — principles, however, of a different kind and not all 

 of the same kind. Among them the source whence 

 the movement comes ^ must be reckoned as one, 

 and that is why the heart is the first part which all 

 blooded animals have, as I said at the beginning <^ ; 

 in the other animals it is the counterpart of the 

 heart that is formed first. 



Beginning at the heart, the blood-vessels extend 

 all over the body. They may be compared to the 

 skeleton models which are traced out on the walls of 

 buildings,"^ since the parts are situated around the 

 blood-vessels, because they are formed out of them. 

 The formation of the uniform parts is effected by the The 

 agency of cooling and heat ; some things are " set " ^r^™ 

 and solidified by the cold and some by the hot. I 

 have spoken previously elsewhere " of the difference 

 between these, and I have stated what sort of things 

 are dissoluble by fluid and by fire, and what sorts are 

 not dissoluble by fluid and cannot be melted by fire. 

 Resuming then : As the nourishment oozes through 

 the blood-vessels and the passages in the several 

 parts (just as water does when it stands in unbaked 



■* Cf. H.A. 5l5a.Sa. Hesychius's and Photius's definitions 

 of Kttva/Soi describe them as the woodwork around which 

 modellers, when they begin their modelling, mould the wax 

 or plaster. There is a similar passage in Parts of A n imals, 

 though without mention of this term (654. b •29) ; there 

 Aristotle speaks of a " hard and solid core or foundation " 

 round which the figure is modelled ; though in that case he is 

 speaking of the bones. There seems to be no justification 

 for interpreting KovajSoi as a mere outline or sketch ; nor 

 would such a meaning fit the passage. Cf. 764. b .SI. 



' Meteorologica, Bk. IV, chh. 7-10. Cf. also 762 a 31. 



219 



