210 OBSERVATIONS ON THE CHANGES OF 



nature seems to be so simple, that it can be easily comprehended ; but 

 if a different and opposite process is observed, in giving new and en- 

 tirely different colours to the old feathers of the bird in spring, the law 

 of nature, so uniform in other respects, cannot be traced. The fea- 

 thers and other appendages in birds may (without adopting the nice 

 distinctions and scientific terms used in botanical science) be compared 

 to the leaves and other appendages of plants. In early spring, the 

 juices, together with the influence of sun and air, impart that nourish- 

 ment which causes the leaf to expand, and assume its beautiful colours ; 

 but when the leaf has arrived at maturity, no fresh growth of the tree 

 will give a new colouring to its leaves. New ones maybe formed, 

 and these may continue to grow and flourish, but the old ones fade and 

 drop ofl". Even among our evergreens of the south, whose leaves are 

 persistent, as the orange tree, &c., which may be said to have tvs'o pe- 

 riods of growth (April and September), the leaves, when once ma- 

 tured, seem to have lost the power of further circulation ; they cease 

 to grow ; their rich colours fade ; and they only await the time appointed 

 them by nature, to return to the ground. If the feathers in birds, 

 then, which have been long stationary in their growth, are capable of 

 receiving a new set of secretions, and of assuming opposite colours, we 

 must seek for some new law of nature, not hitherto understood. 



The origin of the feathers is the matrix which is placed in the skin, 

 or under it. The structure of the matrix is a pulpy substance called 

 bulb, and a capsule, which is composed of several layers. The bulb 

 furnishes the material of the stem and vane, which, when complete, 

 disappears, leaving no residue but the almost imperceptible ligament, 

 connecting the quill to the bottom of the cavity, which receives and 

 embraces it. Whenever a new feather is to be formed, a new matrix 

 is necessary to the process. The early connection of this matrix with 

 the body, is by means of vessels. From these the pulp or bulb de- 

 rives its nourishment. The feather is, whilst young, enclosed in a 

 sheath, and this, as well as the quill itself, is filled with a coloured 

 fluid. In a few weeks the secretions have been imparted to the fea- 

 thers, and the sheath, by a process of absorption, becomes dry, and is 

 rubbed off*. In the tube of the feather now remains a jointed mem- 

 branous body, which every one has observed in the barrel of a common 



