[ 476 ] 
not here mean, that the proper Head has a&ualfy 
that Length ; very far from it : But I here give that 
Name alfo to Five or Six Rings, which are contigu- 
ous to the Head properly fo called. It is not fo with 
regard to the Tail, which, having foon furpaffed the 
Head in Length, does not leave off ftill extend- 
ing itfelf; but increafes, from Day to Day, fo 
that I do not yet know how far it may go. I 
fhall content myfelf with faying, that Pieces of thofe 
Worms, which, in the Month oijuly, immediately 
after the Operation, were not quite Two Lines in 
Length, are at prefent near Two Inches long : But 
what may be thought more remarkable, is, that fome 
fuch Pieces have made in the fame time as much 
Progrefs, as others Four or Five times as long. I have 
compared the different Growths of the Fir ft Moiety 
of a Worm about Two Inches long, cut on the i 8th 
of July, with thofe of fome of the Pieces of a like 
Worm cut the fame Day into Eight Pieces; and was 
furprifed to find the Quantity of Growth near the 
fame in both Cafes. However, it appeared that 
when the Divifion was yet carried further, the Pieces 
thence arifing reproduced what they wanted more 
flowly than the others. 
But, if, inftead of making this Comparifon between 
the Pieces of different Worms, we make it between 
thofe of the fame Worm, we fhall obferve Varia- 
tions which we perhaps would not have expected. 
Some of thcfe Pieces will be Twelve or Fifteen Lines 
long, whilft others will hardly be Four or Five. I 
have done my utmoft to find among thofe Variations', 
fome fixed Point, fome Rule, not contradi&ed by 
Experience; and it has appeared to me in general, that 
