COMPARATIVE ANATOMY. 127 



and firm as if nothing had happened to it. Draw your fin- 

 ger down the feather, which is against the grain, and you 

 break, probably, the junction of some of the contiguous 

 threads ; draw your finger up the feather, and you restore 

 all things to their former state. This is no common con- 

 trivance ; and now for the mechanism by which it is ef- 

 fected. The threads or laminae above mentioned are inter- 

 laced with one another ; and the interlacing is perform- 

 ed by means of a vast number of fibres or teeth, which 

 the laminse shoot forth on each side, and which hook and 

 grapple together. A friend of mine counted fifty of these 

 fibres in one twentieth of an inch. These fibres are crook- 

 ed ; but curved after a different manner ; for those, which 

 proceed from the thread on the side towards the extremity 

 of the feather, are longer, more flexible, and bent down- 

 ward : whereas those which proceed from the side towards 

 the beginning or quill end of the feather are shorter, firm- 

 er, and turn upwards. The process then which takes 

 place is as follows. When two laminse are pressed togeth- 

 er, so that these long fibres are forced far enough over the 

 short ones, their crooked parts fall into the cavity made by 

 the crooke<l parts of the others ; just as the latch that is 

 fastened to a door, enters into the cavity of the catch 

 'fixed to the door post, and, there hooking itself, /aspens the 

 door ; for it is properly in this manner, that one thread of 

 a feather is fastened to the other. 



This admirable structure of the feather, which it is easy 

 to see with the microscope, succeeds perfectly for the use 

 to which nature has designed it, which use was, not only 

 that the laminae might be united, but that when one thread 

 or lamina has been separated from another by some exter- 

 nal violence, it might be reclasped with sufficient facility 

 and expedition.* 



In the ostrich, this apparatus of crotchets and fibres of 

 hooks and teeth, is wanting ; and we see the consequence 

 of the want. The filaments hang loose and separate from 

 one another, forming only a kind of down ; which consti- 

 tution of the feathers, however it may fit them for the flow- 

 ing honours of a lady's head-dress, may be reckoned an 

 imperfection in the bird, inasmuch as wings, composed of 

 these feathers, although they may greatly assist it in run- 

 ning, do not serve for flight. 



* The above account is taken from Memoirs for a Natural History of 

 Aflimajs by the Royal Academy of Paris, published 1701, p. 219, 



