in their Structure and Functiotis, \ 393 



tilla Anserina, it is silky ; and in the Ferbascum Thapsus, 

 or great mullein, it is so thick and tough as to bear a strong 

 resemblance to flannel. The clothing, or, as it is termed, 

 the pubescence of plants, is evidently intended as a protec- 

 tion against cold : for we find that the plants which grow on 

 mountains or in cold situations are always clothed with a 

 woolly investment ; and it is remarked that this investment 

 is generally thickest on those parts which are most exposed 

 to the winds. The pubescence of vegetables falls off at cer- 

 tain seasons of the year, and its original appearances and 

 character are considerably changed by cultivation. In ani- 

 mals, as in plants, the surface is sometimes naked; but for 

 the most part clothed with a variety of substances, such as 

 down, hair, wool, quills, and feathers. These investments 

 present every variety of character that can be imagined; 

 being adapted not only to the peculiar nature of the animal 

 itself; but to the climate which it inhabits. In cold regions, 

 where the injurious effects of a low temperature are to be 

 guarded against, the hair is thick and long, and the plumage 

 is downy; while in warmer countries, where the temperature 

 of the body is more upon an equality with that of the sur- 

 rounding atmosphere, the hair is thin and short, and the 

 feathers almost destitute of down. The clothing of animals 

 is cast off once or twice in the year, and by domestication its 

 original qualities are remarkably altered. The surface of 

 plants, besides the pubescence, is also furnished with prickles, 

 stings, and thorns, which may be considered as organs of 

 defence. The first two, like the wool and hair, are modified 

 from the epidermis. Animals are provided with similar 

 weapons, most of which are derived from the cuticle. It is 

 from this substance that the claws of the tiger and the cat, 

 the talons of the eagle, and the quills of the porcupine, are 

 all produced. The sting of the nettle, and that of the wasp, 

 are not only composed of nearly the same materials, but are 

 constructed on precisely the same principle. The former, 

 when examined with a microscope, appears to be a stiff, highly 

 polished tube, possessing an extremely fine point : at its base 

 is situated a small bulb, which secretes the venomous liquid. 

 When the sting enters the skin, the bulb is pressed upon ; 

 the poison rises in the tube, escapes through an aperture in 

 its point, and is instilled into the wound. To this, the sting 

 of the wasp presents an exactly corresponding formation, 

 except that the channel along which the poison passes does 

 not open at the very point, but at a short distance behind it. 



( To be continued-') 



