j g 2 M i c r o s c o p i c a l E s s a y s .
were into a new world, and become acquainted not only with a
few unknown animals, but with numerous fpecies thereof, which
are fo finguiar in their formation and habits, that without the
cleareft proofs even their exiftence would not be credited; and
while they afford frefh inftances o f the Creator’s power, they alfo
give further proofs o f the limits and weaknefs o f the human
underftanding.
D i r e c t i o n s f o r f i n d i n g , f e e d i n g , a n d p r e s e r v i n g
t h e P o l y p e s .
Thefe little animals are to be found upon all forts of aquatic
plants, upon branches o f trees, pieces of board, rotten leaves,
Hones, and other fubftances that lie in the water; they are alfo to
be found upon the bodies of feveral aquatic animals, as on the
water-fnail, on feveral fpecies of the monoculus, &c. they generally
fix themfelves to thefe by their tail, fo^thatit is a very good
method when you are in fearch of polypes, to take up a great
many of thefe fubftances, and put them in a glafs full ©f water-
I f there be any polypes adhering to thefe, you will foon perceive
them ftretching out their arms, efpecially i f the glafs is let Hand
ftill for a while without moving i t ; for the polypes, which contract
themfelves -on being firft taken out o f the water, will foon
extend themfelves again when they are,at reft.
T he y are to be fought for in the corners o f ditches, puddles,
and ponds, .being generally driven into thefe with the pieces of
wood or leaves to which they have attached themfelves. They
■ may, therefore, he fouglit for in vain at one period, in a place
where at another you {hall find them in abundance. They are
more eafily perceived in a ditch when the fun fhines on the bottom,
than at another time. They are feldom to be met with in
winter: about the month o f May they begin to appear and
increafe.
They are generally to be found in waters which move
gently; for neither a rapid ftream, nor ftagnant waters, ever
abound with them. As they are always fixed to fome fubftance
by their tails, and are very rarely loofe in the water, taking up
water only can lignify but little ; a circumftance which has probably
been the caufe of much difappointment to thofe who have
fearched for them.
The green polypes are generally about half an inch long when
ftretched o u t; thofe of the fecond and third fort are between
three quarters of an inch and an inch in length; though fome
are to be found at times which are an inch and a half long.
Heat and cold has the fame effect upon thefe little creatures,
that it has upon thofe o f a larger fize. They are animated and
enlivened by heat, whereas cold renders them faint and languid ;
they Ihould therefore be kept in fitch a degree of heat, that the
water may not be below temperate.
It is c o n v e n i e n t f o r m a n y e x p e r im e n t s t o f u f p e n d a p o l y p e
f r o m t h e f u r f a c e o f t h e w a t e r . T o e f f e c t th i s , t a k e a h a i r p e n c i l
in o n e h a n d , a n d h o l d a p o in t e d q u i l l in t h e o t h e r ; w i t h th e
p e n c i l lo O fe n t h e p o l y p e f r o m t h e r e c e i v e r in w h i c h i t is k e p t ,
a n d g r a d u a l l y r a i le i t n e a r t h e t o p o f t h e w a t e r , f o t h a t t h e a n t e r
i o r e n d m a y b e n e x t t h e p o in t o f th e p e n c i l ; t h e n l i l t i t o u t o f
U ^