II. Obferyations upon the Bones' and the Perio- 
ileum, in a Letter to the Royal Society, from 
Mr. Leeuwenhoek, F. ^ S. 
Delfr, Nov. 20. 1720. 
S O ME Years ago, I communicated to the Ropl 
r/nZ J ' my Obfetvat ions upon the Bones; what 
L"°_ Obfervations were, I do not notv remember, nor 
have I endeavour d to recoiled them, left I might be 
" y “"* »«" 
In my laft Letter I acquainted you, that I had fe- 
ver a I times endeavour’d to difeover, after what man- 
ner the l en often m was united to thole VciTcls, that 
compofe the Bone, but that I had not been able to 
obferve >t to my fatisfadion. Since which time 1 have 
frequently employ’d myfelf i„ making Obfervations 
upon the Bones, and have found that the fuperficial 
con f l ^. ec * ofan inconceivable number of 
(mail Veffels, and fome few of a larger fize, which 
laft, when they came to the furface of the Bone ap- 
pear d ro me to be cloathed with either a Membrane 
or a bony Subftance, that was perfedly tranfparcnr. ’ 
I once happen d to difeover in a fmall portion of a 
Shinbone, four or five Veflels of fuch a fize tha a 
Angle fiiament of Silk might have been drawn tluo’ 
their Aperture. One of thefe appear’d to me to con 
fift of two openings, each of which feem’d to be pro- 
° vided 
