. XXXIX. 3. 3. GENERATION. 387 



on the head ; and in the growth of our nails from the fpecks 

 fometimes obfervable on them ; and in the increafe of the white 

 crefcent at the roots, and in the growth of new flefh in wounds, 

 which confifls of new nerves as well as of new blood- veflels. 



3. Laftly, Mr. Buffon has with great ingenuity imagined the 

 exiftence of certain organic particles, which are fuppofed to oe 

 partly alive, and partly mechanic fprings. The latter of thefe 

 were difcovered by Mr, Needham in the milt or male organ of a 

 fpecies of cuttle fi(h, called calmar ; the former, or living animal- 

 cula, are found in both male and female fecretions,in the infufions 

 of feeds, as of pepper, in the jelly of roafted veal, and in all other 

 animal and vegetable fubftances. Thefe organic particles he 

 fuppofes to exift in the fpermatic fluid of both fexes, and that 

 they are derived thither from every part of the body, and muft 

 therefore refemble, as he fuppofes, the parts from whence they 

 are derived. Thefe organic particles he believes to be in con- 

 ftant aftivity, till they become mixed in the womb, and then 

 they inftantly join and produce an embryon or fetus fimilar to 

 the two parents. 



Many objections might be adduced to this ingenious theory ; 

 I (hall only mention two. Firft, that it is analogous to no 

 known animal laws. And fecondly, that as thefe fluids, replete 

 with organic particles derived both from the male and female 

 organs, are fuppofed to be fimilar ; there is no reafon why the 

 mother (hould not produce a female embryon without the af- 

 fiftance of the male, and realize the lucina fine concubitu. See 

 No 8 and 9 of this feclion, and Sea. XXXVII. 3. 



IV. i. I conceive the primordium, or rudiment of the em- 

 bryon, as fecreted from the blood of the parent, to confift of a 

 fimple living filament as a mufcular fibre ; which 1 fuppofe to 

 be an extremity of a nerve of locomotion, as a fibre of the reti- 

 na is an extremity of a nerve of fenfation ; as for inftance one 

 of the fibrils, which compofe the mouth of an abforbent veflel , 

 I fuppofe this living filament,of whatever form it may be, wheth- 

 er fphcre, cube, or cylinder, to be endued with the capability of 

 being excited into aclion by certain kinds of (limulus. By the 

 ilimulus of the furrounding fluid, in which it is received from 

 the male, it may bend into a ring : and thus form the beginning 

 of a tube. Such moving filaments, and fuch rings, are defcribed 

 by thofe, who have attended to microfcopic animalcula. This 

 living ring may now embrace or abforb a nutritive particle of 

 the fluid, in which it fwims ; and by drawing it into its pores, or 

 joining it by comprefiion to its extremities, may increafe its own 

 length or craflitude ; and by degrees the living ring may become 

 a living tube. 



2. With 



