ON GENERATION. 417 



and run. Infants, therefore, resemble dwarfs in the beginning, 

 and they creep about like quadrupeds, attempting progres- 

 sive motion with the assistance of all their extremities ; but 

 they cannot stand erect until the length of the leg and thigh 

 together exceeds the length of the rest of the body. And so 

 it happens, that when they first attempt to walk, they move 

 with the body prone, like the quadruped, and can scarcely rise 

 so erect as the common dunghill fowl. 



And so it happens that among adult men the long-legged 

 they who have longer legs, and especially longer thighs are bet- 

 ter walkers, runners, and leapers than square-built, compact men. 



In this second process many actions of the formative faculty 

 are observed following each other in regular order, (in the same 

 way as we see one wheel moving another in automata, and 

 other pieces of mechanism,) and all arising from the same mu- 

 caginous and similar matter. Not indeed in the manner 

 that some natural philosophers would have it when they 

 say, "that like is carried to its like." We are rather to 

 maintain that parts are moved, not changing their places^ 

 but remaining and undergoing change in hardness, softness^ 

 colour, &c., whence the diversities between similar parts 

 those things appearing in act which were before in power. 1 

 The extremities, spine, and rest of the body, namely, are 

 formed, grow, and acquire outline and complexion toge- 

 ther; the extremities, comprising bones, muscles, tendons, 

 and cartilages, all of which on their first appearance were simi- 

 lar and homogeneous, become distinguished in their progress, 

 and, connected together, compose organs, by whose mutual 

 continuity the whole body is constituted. In like manner, 

 the membrane growing around the head, the brain is com- 

 posed, and the lustrous eyes receive their polish out of a per- 

 fectly limpid fluid. 



That is to say, nature sustains and augments the several 

 parts by the same nourishment with which she fashioned them 

 at first, and not, as many opine, with any diversity of aliment 

 and particles similar to each particular structure. As she is 

 increasing the mucaginous mass or maggot, like a potter she 

 first divides her material, and then indicates the head and trunk 



De Gen. Anim. lib. ii, cap. 4. 



27 



