FEATHERS OF BIRDS. 509 



of the longitudinal ^Yhite band, seen in Fig. 229, 

 and wind obliquely upwards till they reach the 

 opposite longitudinal band already described, where 

 they join a longitudinal partition which occupies 

 a line ansvv ering to that posterior band. Thus they 

 leave between them narrow spaces, which consti- 

 tute so many compartments for the deposition, as 

 in a mould, of the material of each lamina. The 

 course of these channels, and their junction at the 

 back of the matrix is seen at s, Fig. 230. It is 

 exceedingly probable, though from the minuteness 

 of the parts it is scarcely possible to obtain ocular 

 demonstration of the fact, that the fibrils of the 

 laminae are constructed in a similar manner, by 

 being moulded in still more minute compartments, 

 formed by transverse membranous partitions. 



The proper office of the bulb, after it has sup- 

 plied the materials for the formation of the laminae, 

 is to construct the stem of the feather, and unite 

 the laminae to its sides. For this purpose the an- 

 terior portion of the bulb deposits on its surface a 

 plate of horny substance, while another plate is 

 formed by the posterior part in the interior of the 

 bulb. Thus the bulb becomes divided into two 

 portions; one anterior, and the other posterior. 

 The former of these, after having finished the 

 external plate, proceeds to form the spongy sub- 

 stance, which is to connect the two plates, and the 

 posterior portion of the bulb embraces the inner 

 plate, and gradually folds it inwards till its sides 

 meet at the middle groove along the back of the 

 stem. The anterior part of the bulb, during the 

 process of filling up the stem, exhibits a series of 

 conical shaped membranes, as is seen in the sec- 



