in the reft of the Blood Veflels of tlie whole Body la a 
healthful ftate. 
Hence it is, when any of the Blood Veffels of the Lungs 
are ftreightened or totally compreft (either or both, which 
Circumftances muft happen in Mrs Tenfs Gafe) the reRai^- 
ing unobftruded Blood Veffels are forced to difcharge EBore 
than they were wont, and in time thofe Veffels become 
fufBciently dilated to fupply the defeft. The like happens 
in the Communicant branches of the Arteries of any part, 
when fome confiderable Branch or Trunk is ty'd up,as in the 
operation for caring of aa Aneurifm. ;^ ViJc mi. 
Thus, Sir, we find the ftrufture of the parts of Animal .so.""?'^^^^^ 
Bodies not only (ufEcient to perform the ordinary operari- T^-e Vuiw 
ons of Nature, but their Organs are. fo wonderfully made, ^^^^j f^^}^" 
that notwithftanding confiderable parts of thofe Organs are perfea heiith 
obftruded, yet their neighbouring parts ( as in the cafe be- v^fg^W/r' 
fore us, the Blood Veffels) becom.e capable of fupplying thetirrufJof his 
defeft. This indeed exafts our gratitude as well as admira*^^«^ 
tion of the Divine Architeft. 
The Explication of the Figures. 
Fig. 1. 
THat part of the 5th Figure at D done by a 
larger Magnifying Glafs, ? e. by the 3d Glafs of the 
Microfcope defcribed No 281. of thefe Tranfaftions. 
A The Arteries. 
B The Veins of a Frogs Lungs prepared as above-menti- 
oned. 
C Their Inofculations with each other. 
D . . • . , The Area of the Microfcope, as it appears to tht 
naked Eye* 
Eeeeeeee 2 
