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any lading detriment to the drudture and fubordina- 
tion of the veflels ; which yet, upon this hypothecs, 
mud have been utterly dedroyed before fuch an irre- 
gularity could have happened. 
The other theory concerning, the origin of the 
lymphatics has been maintained by forne very emi- 
nent phyfiologids later than Boerhaave ; and fup- 
pofes, that thefe veffels receive their lymph from the 
blood-veflels, or from the excretories of the larger 
glands, by the intermediation of only one final! 
veflel, which thefe authors term a lymphatic artery,, 
invisible in its natural date, nor yet rendered fubjedtr 
to the fenfes by experiments. But to this it may be 
anfwered, that the lymphatics are traced into many 
parts of the body,, and loft there } and therefore 
mod probably have their origin there,, where no* 
large gland nor blood-veflel is to be found in their 
neighbourhood that it contradicts the whole ana- 
logy of nature, to fuppofe the motion of an animat 
fluid more difcernible in the veins than in the arte- 
ries : and, finally,, that it feems rather an indance 
of want of thought, and of being impofed upon, 
by words, to call the lymphatic veflels veins, becaufe 
they are furnifhed with valves and then, becaule 
they are called veins, to take for granted, that of 
courfe they mud be the continuation of arteries. 
In attempting to invedigate matters too fubtile for 
the cognizance of our fenfes, the only method, in. 
which we can reafonably proceed,, is by inferring 
from what we know in fubjeCts of the fame nature : 
and our conclufion thus inferred, concerning the fub- 
jeCt fought, will be firmer and more unquedionable,, 
in proportion, as it refembles the fubjeCt known. But 
