f 1789 ^ 
Afterwards, when I lookt upon em ngain, I could not 
perceive the leaft Motion in their Bodies, either irtward 
or outward, but obferved that fonTetimes they fubfided 
in the Water, aud then emerged again, but very leifure* 
ly 5 which appeared very ftrange to me, becaufe, as I 
(aid jull; now, I could not difcover the leaf!: motion in 
their Bodies tho I don't doubt to AiTert.. that there is 
foiiie Motion, be it never fo rmail, in a Body, .which in 
the fpaceof 2 or 9 Pulfes fhall one while fink to the bot- 
tom, and then rife to the top 5 for it is impoffible for us 
to fct an inanimate Body in the. Water in fuch a pofitioo, 
that it fhall neither fink quite down, nor emerge quite 
up to the fuperficies 5 and tho we could find a Body 
( which yet I think is not to be done ) that fhould be juft 
of the fame weight with Water, it could not keep the 
place in the V/ater to which it was firft affign'd 5 for, 
according as the Water, into which you put that Body^ 
fliould encreafe or diminifti in Heat, that ftme Water 
would proportioiiably take up more or lefs Space 3 and 
confequently the Body, that was fo placed that it could 
neither entirely emerge nor fubfide, if the Water, for 
example, ihould become warmer, and fo take up more 
room, would immediatdy fink td the bottom. In fiiort, 
v/e have reafon to be confounded in our imaginations,^ 
when we meet with fuch Animaleula as ! before defcrib'd. 
The only Solution therefore that I can give in this cafe, 
is, That fuch an Animalculum has fome Air in its Body, 
and that by fqueeziog and contrafting of its Body it can 
emit fome of the Alateria S^ibtilk that is mixt with it, by 
which it naturally fubfides 5 and on the contrary, by di* 
lating its Body again, an equal quantity of the f^me 
Materia Snkilk is let in, and fo the Animalculuni, with- 
out ftirring itfelf, fliall rife or fiok. 
Now I was the more ealily induced to fay v^hat I for- 
merly did about the Animaleula that are faftned to the 
Roots of Duck" weed s to wit, that they had two dil^invT: 
X X X X X x'x X X X a re- 
