192 LYMPHATIC SYSTEM. 



ing the intestine and cutting the villi across he observed them 

 spongy. 1 But this is an appearance which may be as well ex- 

 plained, from knowing that each villus contains a network of 

 small arteries and veins, which being inflated might occasion the 

 villi to assume a spongy appearance. 



Since then the experiments from which the villi of the 

 human subject were supposed to contain an ampullula are so 

 equivocal ; and since the villi can be proved in the other classes 

 of animals, viz. in birds, fish, and the amphibia, to have net- 

 works of lacteals as well as of arteries and veins, the probability 

 is in favour of their having the same structure in the human 

 subject. But the difference between us is inconsiderable ; for 

 it may be nearly the same thing whether there is a bag filled 

 with sponge, or a plexus of vessels. 



I have some preparations by me adapted to the microscope 

 in Lieberkiihn's manner, in which I think I can clearly show 

 the orifices of the lacteals on the extremities of the villi, where 

 there appears, as he has described, sometimes to be one, and 

 sometimes more orifices. 2 My preparations were made by in- 

 jecting into both arteries and veins a thin size or glue, coloured 

 with vermilion ; when this was not pushed to great minute- 

 ness the villi appeared exactly as Lieberkiihn has painted them, 

 with a network of arteries and veins on each, and when ex- 

 amined with a microscope no orifices could be distinguished, 

 but each villus appeared to have a smooth edge. Yet in some 

 part of the ileum where the injection had run more minutely, 

 the villi appeared erected, and instead of being broad and thin 

 were more round and cylindrical, and the extremity seemed 

 spongy and porous, whilst all the sides of the villus were per- 

 fectly smooth and uniform. And moreover as in these prepa- 

 rations the orifices only appeared when the villi were completely 

 erected, I think this circumstance points out the use of the 

 villi.. 



It might be here objected that these were only lacerations 

 of the villi, but I am persuaded they were not, from having, on 

 repeatedly examining them, observed the pores or orifices very 

 distinct and empty ; whereas, were they lacerations, I think I 

 should have seen the injection in them, as the villi were so 

 much distended by it. 



1 De Villis Intest. 8. 2 Ibid. 3 (See Notes LXXXIII and LXXXVI). 



