OF NATURAL HISTORY. 41 



Animals have long been divided into viviparous and ovipa- 

 rous. The one clafs produce their young alive, the other 

 lay eggs, which muft be hatched either by the heat of the 

 fun, or by that of the mother. This divifion, though very 

 comprehenlive, is not perfedt. Several animals have lately 

 been difcovered which are neither viviparous nor oviparous ; 

 and there are animals which unite both thefe modes of mul- 

 tiplication. 



The viviparous clafs comprehends men, quadrupeds, and 

 fome fiflies, reptiles, and infedls. The oviparous includes 

 birds, fome reptiles, and mofi: of the infe£t tribes. But the 

 armed polypus, or hydra of Linnaeus, inflead of being either 

 viviparous or oviparous, multiplies its fpecies, as formerly 

 remarked, by fending off fhoots from the body of the parent. 



Another fpecies, called the hell-polyptiSy or hydra ficntorca of 

 Linnaeus, multiplies by fplitting longitudinally. In twenty- 

 four hours, thefe diviiions, which adhere to a comiT.on 

 pedicle, refplit, and form four diRindl animals. Thefe four, 

 in an equal time, again fplit \ and thus they proceed doub- 

 ling their numbers daily, till they acquire a figure fomewh^t 

 refembling a nofegay. The young afterwards feparate from 

 the parent ftock, attach themfelves to the roots or leaves of 

 aquatic plants, and each individual gives rife to a new colony. 



The funnel-fliaped polypus multiplies by fplitting tranf- 

 verfely. Of the individuals, accordingly, which proceed 

 from this diviiion, one has the old head and a new tail, and 

 the other a new head and the old tail. The fuperior divliioii 

 fwims off, and fixes jtfelf to fome other fubflance ; but the 

 inferior diviiion remains attached to the former pedicle. 



The dart-millepes affords another example of multiplica- 

 tion by fpontaneous feparation. This infecl divides, about 

 two-thirds below the head. Into two diflin^l and perfect ani- 

 mals ; and it feems to poffefs no other mode of continuing 

 the fpecies. 



