GENERATION OF ANIMALS, II. vi. 



Now the upper portion of the body is the first to be 

 marked off in the course of the embrjo's formation; 

 the lower portion receives its gro^\i:h as time o^oes on. 

 (This applies to the blooded animals.) In the early 

 stages the parts are all traced out in outline ; later 

 on they get their various colours and softnesses and 

 hardnesses, for all the world as if a painter were at 

 work on them, the painter being Nature. Painters, 

 as we know, first of all sketch in " the figure of the 

 animal in outline, and after that go on to apply the 

 colours. 



As the source of the sensations is in the heart, 

 the heart is the first part of the whole animal to be 

 formed ; and, on account of the heat of the heart, 

 and to pro%ide a corrective to it, the cold causes the 

 brain to " set," where the blood-vessels terminate 

 above. That is whv the regions around the head Brain, 

 begin to form immediately after the heart and are 

 bigger than the other parts, the brain being large 

 and fluid from the outset. 



The development of the eyes is something of a Eyes, 

 puzzle to the student. In birds, beasts, and fishes 

 alike, the eyes are from the outset ver}" large in 

 appearance, yet they are the last of all the parts to 

 be completely formed, since they shrink up in the 

 meantime.*' The reason is that the sense-organ of 

 the eyes is indeed, like the other sense-organs, set 

 upon passages ; but whereas the sense-organ of touch 

 and of taste is just the animal's body or some portion 

 of the body, and smell and hearing are passages 

 full of connate pneuma,'^ connecting \nth the outer air 

 and terminating at the small blood-vessels around 



' Cf. note, 740 a 28. » C/. H.A. 561 « 19 ff. 



' See App. B §§ 26 ff. 



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