424 ON GENERATION. 



needful to the being or to the maintenance of the individual, 

 but only as defences against external injury, as ornaments, or 

 as weapons of offence. 



The outermost part -of all, the skin, with its several append- 

 ages, cuticle, hair, wool, feathers, scales, shells, claws, hooves, 

 and other items of the same description, may be regarded as 

 the principal means of defence or protection. And it is well 

 devised by nature, who, indeed, never does aught amiss, that 

 these parts are the last to be engendered, inasmuch as they could 

 never be of use or avail as defences until the animal was born. 

 The common domestic pullet is therefore born covered with 

 down only, not with feathers, like certain other birds which have 

 to be speedily prepared for flight, because it has to seek its food 

 on foot, not on the wing, and by active running about hither 

 and thither. In like manner the young of ducks and geese, 

 which feed swimming, have their feathers and wings perfected 

 at a later period than their feet and legs. It is otherwise with 

 swallows, however, which have to fly sooner than to walk, be- 

 cause they feed on the wing. 



The down of the pullet begins to appear after the fourteenth 

 day, the foetus being already perfect in all its parts. When 

 the feathers first show themselves, they are in the guise of points 

 within the skin, but by and by the feathers project, like plants 

 from the ground, increase in length, become unfolded, invest 

 the whole body, and protect it against the inclemencies of the 

 atmosphere. 



Feathers differ from quills in form, use, place of growth, 

 and order of production. The pullet is feathered before it 

 has any quills, for the quill-feathers only grow in the wings 

 and tail, and also spring more deeply, from the very lowest 

 part of the integument, or even from the periosteum, and serve 

 essentially as instruments of motion ; the feathers again arise 

 superficially from the skin, and are everywhere present as means 

 of protection. 



" Nails, hair, horn, and the like," says Aristotle, 1 " are en- 

 gendered from the skin ; whence it happens that they change 

 colour with the skin ; for the white and black and particoloured 

 are so in consequence of the colour of the skin whence they 



1 De Gener. Anim. lib. ii, cap. 1. 



