( k*o ) 
XVI. A Letter from Mr. Anthouy van Leeuwen- 
hoek, F. S- containing fome further Microfco- 
pical ObJerVations on the Animalcula foun& upon 
Duckweed, See. 
Delft , June 28. 1713. 
my Letter of the 4th of November , 1 7 04. I took 
Notice of the wonderful Figure of an Animalculum^ 
tnat was fix’d in a little Scabboard or Sheath, faken’d to 
fome of the fmall green Weeds that are found in Ditches 
foil of Water. It is aeferihed in the fiid Letter by 
Fig. 1. [See Philofoph. Tranfaft. No. 29 5- 1 ] 
As often ss I have view’d thefe Animalcule and coni' 
municared the Sight of ’em to others, we could not Latisfy 
our felves with looking upon fuch wonderful Creatures 5 
and the more, beciufe we could not conceive how fo 
furprizing a Motion, as all of ’em had, could be per- 
form’d j as alfo what fhould be the ufe of fuch a Mo- 
tion. For when vve obferve other Creatures, that are en- 
dued with Motion, moving any Parts of their Body, we 
prefently conclude, that the Parts which they move, are 
not created in vain $ and confequently we may affert. that 
the -wheel- like Motion of the above-mentioned Animal- 
cula , is ufeful to their Bodies, tho’ we, cannot tell ex- 
actly how. 
In the latter end of July^ and in the beginning of 
Jugufl laft, I caus'd fome of thofe green Weeds, which 
they commonly call Duck-Weed, to be taken out of the 
Water, that runs with a gentle Stream thro 1 the Town, 
