ANIMAL ORGANIZATION. 



1-21 



containing an unctuous matter. During the 

 formation of the quill this unctuous matter is 

 supplied through this channel, and probably 

 enters as an ingredient in its composition. The 

 capsule of the pulp consists of two membranes, 

 the one enveloping the other. Fig. 36 shows 



the bulb laid open by dividing the membranes 

 and turning them aside. The horny portion 

 of the quill is secreted by the internal mem- 

 brane, i, and deposited in successive laminae. 

 The external membrane is seen at o. The 

 pulp itself, seen at p, is still more curiously 

 organized ; its surface being fluted, or formed 

 into longitudinal processes. The horny matter, 

 being deposited on these processes, is moulded 

 to their shape, and concretes into laminae which 

 converge from the circumference of the cylin- 

 der towards the centre. The section (Fig. 36') 



