OF NATURAL HISTORY. g91 



CHAPTER XII. 



Of the Transformation of Anhnah. 



1 HE transformation of caterpillars, and of dif- 

 ferent kinds of worms, into winged infe(Sts, has long excited 

 the attention, as well as the admiration of mankind. But 

 the truth Is, that every animal, without exception, undergoes 

 changes in ftruiSlure, mode of exiftence, and external appear- 

 ances. Mankind, from their embryo ftate, to their final 

 dilTolution, aflume many different forms. Some weeks after 

 conception, the rudiments of a human being are to be per- 

 ceived. As pregnancy advances, the approaches to the per- 

 fect figure become gradually more difi:inguifhable, till the 

 period of birth. While in the foetus fi:ate, the head is dif- 

 proportionally large, when compared with the other parts 

 of the body ; nourifliment is conveyed to it by very differ- 

 ent channels ; and refpiration is not necelTary, becaufe the 

 circulation of the blood is not carried on in the fame manner 

 as after birth. Even after birth, the form, fymmetry, and 

 organs of the animal are by no means complete. The head 

 continues for fome time to be difproportionally large •, the 

 hands and feet are not properly fhaped ; the legs are crook- 

 ed \ the hair on the head is fhort and fcanty ; no teeth as 

 yet appear -, and there is not a veftige of a beard. In a few 

 months, however, the fymmetry of all the parts is evidently 

 improved, and the teeth begin to fhoot. The growth of the 

 whole body, as well as the flrength and beauty of its form 

 gradually advance to perfection till the fixth or feventh yecir, 

 when another change takes place. At this period, the firft 

 fet of teeth are fhed, and are replaced by new ones. From 

 boyhood to puberty, the fize of the body, and of its differ- 

 ent members, increafe. When the age of puberty arrives. 



