4°6 



Microscopical Essays. 



fcope, at Fig. 6, 7, 8, Plate XXIII. A ; it's mouth was at the 

 anterior end a, Fig. 8, of one of thele parts. The tail was at 

 the end b of the third part, Fig. 6 : as this piece was alio per- 

 forated, it plainly appears, that the tail of the hydra is open. 

 The perforation, which is thus continued from one end to the 

 other, is called the ftomach, becaufe it contains and digefts the 

 aliments. The Ik in which inclofes the bag, and forms the 

 ftomach, is the fkin of the polype itfelf ; fo that the animal may 

 be faid to confift of but one fkin, difpofed in the form of a tube, 

 or gut, open at both ends. On opening the polype, no veffek 

 are to be difiinguifhed ; and whatever be the nature of it's orga- 

 nization, it muft refide in the fkin. 



The fkin muft be fo far organized, as to perform all the opera- 

 tions negeflary for the nutrition and growth of the animal, with- 

 out eonfidering thofe that are necefiary for it's various motions* 

 Whatever are the means the Author of nature has employed for 

 thefe purpofes, we are ignorant of them. If their fkin is examined 

 by a microfcope, it appears hke ihagreen, or as if it were cover- 

 ed with little grains ; thefe are more or lefs feparated from each 

 other, according to the degree in which the body is extended or 

 contracted. 



If the lips of a polype be cut tranfverfely, and placed fo that 

 the cut part of the fkin may lie directly before the microfcope, 

 the fkin throughout it's whole thicknefs will be found to confift of 

 an infinite number of thefe grains. To know whether the infide 

 of the ftomach was formed of firmlar grains, feveral of them 

 have been laid open and examined by the microfcope ; the inte- 

 rior fun ace was then found to confift of an immenfe number of 



them, 



