VOL. XXII.] PHILOSOPHICAL TRANSACTIONS. 633 



after 3 hours opening the dog a second time, I observed several of the lacteals of 

 a bluish colour ; which, upon stretching the mesentery, disappeared several 

 times ; but was most easily discerned when the mesentery lay loose ; an argu- 

 ment that the bluish colour was not properly of the vessel, but of the liquor 

 contained in it. 



A few days afterwards, repeating the experiment, with the solution of stone- 

 blue in fountain water, on a dog that had been kept fasting 36 hours, I saw 

 several of the lacteals become of a perfect blue colour, within a very few minutes 

 after the injection : for they appeared so before I could sew up the gut. 



About the beginning of March following, having kept a spaniel fasting 36 

 hours, and then syringing a pint of a deep decoction of stone-blue with com- 

 mon water into one of the small guts ; and after three hours opening the 

 dog again, I saw many of the lacteals of a deep blue colour. On cutting several 

 of them, they afforded a blue liquor, viz. some of the decoction running out on 

 the mesentery. After this I examined the ductus thoracicus, on which, to- 

 gether with other vessels near it, I had upon my return made a ligature, and 

 saw the receptaculum chyli, and that duct of a bluish colour ; not so blue in- 

 deed as the lacteals, from the solution mixing with lympha, in and near the 

 receptaculum, but much bluer than the duct uses to be, or than the lymphatics 

 under the liver were, with which I compared it. 



The entrance into the lacteals (which is much the narrowest part of all the 

 passages from the mouth to the mass of blood) being thus proved beyond ex- 

 ception to be wide enough to admit so gross a body as stone- blue, we may 

 here in part explain the admission of liquors, as of diuretic waters, &c. into the 

 vessels in vast quantities, in a very little time. The same width of the lacteals 

 makes them ready to receive those grosser bodies, conveyed in proper vehicles 

 which afterwards compose the grumous part of the blood, the cartilages and the 

 bones. And this open entrance being allowed, it will no longer seem im- 

 possible, that with our nourishment, eggs or animalcula themselves should 

 enter these vessels ; there being no manner of question, but that of both the 

 one and the other some are much less in bulk than the larger particles of in- 

 digo, in the decoction above-mentioned, seen in the lacteals. Add to this the 

 many species there are of small insects, and their great fertility; so many and 

 so great, that a very small proportion, perhaps not a quarter part, comes with- 

 in view of the naked eye ; then we shall be the better able to account for the 

 great variety, as well as numbers of insects observed in the juices of the animal 

 body. 



But the chief use of the wideness of the lacteal orifices, is in deducing from 

 thence the reception of gross matter, such as are the effects of indigestion, &c. 



VOL. IV. 4 M 



