1 6 Of the Circulation of the Blood. 
particularly in every Tingle toe, and through its fins or 
pointed branches. The blood may be feen running 
through an artery towards the extremity, and returning 
through a vein, with which its communication is very 
apparent, and furprifingly delightful. 
Mr. Leeuwenhoek informs us, that he has obferved 
the circulation of the blood, in the farther!; joints of little 
crabs 1 hinder legs, with greater rapidity than in any 
other creature, and that their red globules were twenty- 
five times fewer than in any other land or water animal 
he had before examined. 
Exceeding fmall crabs may be found under brickbats 
and ftones, on the Ihores of the river Thames, when the 
tide is out. 
The circulation of the blood may be feen in the legs 
and tails of fhrimps, if view’d in water, wherein you 
have mixed a little fait; but in thefe the blood is not red. 
I have frequently feen a fluid flowing through the 
filmy wings of grafshoppers, of a greenifh colour. 
The motion of the blood is alfo to be feen in the tran- 
fparent legs and feet of fmall fpiders, and in the legs of 
very fmall buggs, and an extraordinary vibration of the 
reflels not difcernable in other creatures. 
You may often obferve in viewing feveral of thofc v 
objects, the globules cannot pafs through the fmaller 
vefiels, otherwife than Angle, and then fqueezed into an 
oval form 
If a little frog’s fpawn, in the fpring time, be kept a 
few days in fome of the ditch-water, in which it is found, 
you’ll have a great number of exceeding fmall tadpoles, 
which at their firfl: beginning to fwim, are nearly tran- 
fparent; place them before the microfcope in a fmall 
tube, with a little water, or in a cylindrical glafs, and 
you 
1 Arc. Nat. Tom. iv. Ep. 84, and 86. 
