SECT. XXXIX. 9. 5. GENERATION. 429 



above delivered ; which latter fuppofes, that no organized par- 

 ticles are fecreted either by the glands of the male or female ; 

 but that the fibrils with formative appetencies are fecrered by 

 the glands of the male, and the molecules with formative apti- 

 tudes or propenfities are fecreted by thofe of the female 5 and 

 that, when thefe combine, the organization commences. 



5. If the whole of the embryon is fuppofed to be fynchron- 

 ouily produced, which is faid almoft to be viiible in the cicatric- 

 ula of the egg even before incubation, how can this happen 

 from a commixture of any kind of particles deduced from both 

 the male and female parents, if thofe particles are previoufly dr- 

 tached from the various parts of their refpeHve bodies ; fmce 

 no parts fimilar to the female organs can previoufly exift in the 

 male, nor any of thofe of the male organs previoufly exift in the 

 female ? This fynchronous production of all the parts of the em- 

 bryon is fuppofed by M. BufTbn, and militates againft his the- 

 ory ; and if it was true, would equally militate againft that 

 above delivered ; but from all the hittories of the beginning and 

 growing fetus given by anatomifts there are parts of fecondary 

 formation, as well as parts of primary formation ; thus the head 

 and fpine of the back are firft feen both in the oviparous and vi- 

 viparous embryon, and afterwards the lungs, ribs, limbs, nails, 

 hairs, and feathers, and laft of all perhaps the glands which dif- 

 tinguifh the fexes ; as thefe are the laft, which afterwards ar- 

 rive at their maturity. 



This fecondary formation of parts is evinced in the long cau- 

 dexes of the buds of trees, which form a filament of the bark ; 

 as from any part of this a new plumula or leaf, which is the 

 lungs of the embryon bud, can be produced, when the upper 

 part of a branch is lopped off, as fhewn in No 9, 4. of this 

 iedlion ; and is further evinced in fome animals, as when a 

 common earth-worm is cut in halves, the tail-part can produce 

 a head- part, and the head-part can produce a tail-part ; and 

 laftly, it is evinced from the power, which crabs poileis of gen- 

 erating a new leg, when one of them is accidentally broken off. 

 This power is like wife poflefled by the human body, as in the 

 production of new teeth, and then of a fecond fet, and there are 

 ibme inftances on record, that a third fet of teeth have been fab- 

 ricated in the jaw-bones of age. 



The power of formation of fecondary parts in the human fyf- 

 tem is wonderfully (hewn by the following cafe, which is related 

 by Mr. White in the Mancliefter Memoirs, Vol. I. p. 338. 

 " Some years ago I delivered a lady of rank of a line boy, who 

 had two thumbs on one hand, or rather one thumb double from 

 the iirlt joint, the outer one being rather lefs than the inner, 



and 



