434 GENERATION. SECT. XXXIX. 16. 5. 



activity or quantity of the fibrils with appetencies derived from 

 the male, or the molecules with propenfities derived from the 

 female. This idea differs from the theory of M. Buffon, which 

 fuppofes the whole embryon to be formed at the fame time, or 

 that the fexual organs are firft produced, as a centre of animali- 

 zation ; but the fecondary produftion of thefe organs is agreea- 

 ble to all obfervations on the growing chick or fetus, and is 

 ftrongly countenanced by the flow progrefs of thefe parts after 

 birth, which are not complete till the maturity of the animal, 

 which is termed its puberty. 



The power, which the primary or eiTential parts of the em- 

 bryon poffefs, of producing fecondary or lefs effential parts, is 

 analogous to the production of a new plumula or new radicles 

 by the vegetable embryon, or caudex gemmx mentioned in No. 

 8. 4 of this fection ; and to the power with which crabs are 

 furnifhed to produce a new limb, when one is broken off; and 

 to that of earth-worms, which when cut in halves, can acquire 

 a new head or a new tail ; and to the power in a human infant 

 of regenerating a fupernumerary thumb, to the production of 

 a new fet of teeth, and the developement of the fexual glands 

 at puberty. See No, 9. 5. of this feet ion. 



5. Some of thefe fexual reproductions confift of feeds, or 

 eggs, in which the eflential parts of the vegetable or of the chick 

 are already formed, as may be feen in the corculum of many 

 feeds, and in the cicatricula of an egg, as foon as it leaves the 

 body of the hen before incubation In this (late the embryon 

 does not continue to grow, if expofed only to the ufual degree 

 of the warmth and moifture of the atmofphere, but may be long 

 kept in its itate of infenfible life , though it will foon ferment 

 or putrefy, if it be deprived of life. 



Other wife thefe fexual productions confift of fpawn, which 

 differs from eggs by the embryon not being included in a hard 

 unyielding fhell ; fo that the receptacle diftends, as the fetus 

 increafes in fize ; which is feen in the fpawn of fifti and frogs, 

 and in the eggs of fpiders, fnails,and many other infects. From 

 this diftenfibility of the bag, which contains the embryons of 

 fifh and infects, it feems more to refemble the uterus of quad- 

 rupeds than the eggs of birds ; as in the former the receptacle 

 increafes in fize along with the fetus, and fupplies the liquor of 

 the amnios, as it is wanted ; but differs by its not continuing in 

 the matrix of the mother, till the exclufion of the young animal 

 into the cold and dry atmofphere. 



XL i. Finally we conclude, that as the inanimate particles 

 or atoms of matter unite into cryftals of various forms by the 

 various powers of attraction, which fome kinds of them poffefs ; 



and 



