xliv The Microfcope explained. 
number of the magnifier may be alfo marked on each 
Aider its objedts are fitteft for. Many fmall living ob- 
jedfs may be placed in this manner between the talcs, 
fuch as mites, or any other fmall infedfs which will re¬ 
main alive feveral days. But for prefent examination, 
thefe, as well as larger objedts, may be laid in the hollow 
of a glafs Aider, and that covered with a flat glafs Aider, 
or they may be pinched in the nippers, or ftuck upt>n 
the point as occafion may offer. 
The animalcula in fluids, may be examined in a fmall 
drop of water taken up with the head of a pin or a hair 
pencil, and placed in the hollow of a glafs Aider; if on 
viewing them, you fliould find them exceeding nume¬ 
rous (as is often the cafe,) that by their continual run¬ 
ning over one another, their fhape cannot he diftinguifh- 
ed, fome part of the drop muft be taken off the glafs, 
and a little fair water put to the reft, which will fepa- 
rate, and make them appear diftindt. It is neceflary 
thus to dilute, with fair water, the femen mafculinum 
of all animals ; otherwife their fhape cannot be difcover- 
ed, they are fo crowded together in fuch infinite num¬ 
bers. 
If falts in fluids are to be viewed, you muft let the 
fluid evaporate, that the falts may be left behind upon 
the glafs, and be more eafily examined. 
For viewing the circulation of the blood in the tails of 
fifties, in frogs, newts, &c. they are fometimes put into 
glafs tubes, or tied upon one of the glafs flips or upon 
a fifti-pan which is made to fome microfcopes, or by 
the frog frame in the meflentry of a frog to the higheft 
advantage, as will be hereafter (hewn. 
Patience and dexterity are required to difledt infedfs, 
and view their internal ftrudture, which will be eafily 
done with a fine needle and a lancet; if they are placed 
in a drop of water, their parts will then be feparated 
with 
