TUE INTESTINES. 517 



While digestion is going on, we frequently find the whole parenchyma 

 of the villi densely filled with small nuclei, here and there surrounded 



This difficulty is increased when we consider, tliat a trustworthy observer (Osierlein) has 

 detected soHd particles in tlie interior of the epithelial cells. By assuming, however, that 

 these latter are open at one extremity, and are isolated from the intestinal tube merely by a 

 thin layer of mucilaginous substance, which is easily traversed, Professor Brilcke thinks the 

 difficulty may be solved. The chyle, he states, passes from within the cell through an 

 opening in the opposite extremity into the villus. Within the villus, the molecules of chyle 

 lie in the lacteal and in the interstices of the delicate stroma, which connects the walls of 

 the villus with its muscular fibres and bloodvessels. The lacteal, Professor Brucke regards 

 not as a vessel, but as a mere cavity in the centre of the villus, without distinct walls. In 

 cylindrical villi he generally found one cavity, in broad villi, two, three, or even four dis- 

 tinct canals. Of the structureless, thin membrane, described by KoUiker as surrounding the 

 lactealsf he was not able to observe any traces. He also denies the commencement of the 

 lacteal by a distinct network, as stated by Hewson, Krause, and Hyrtl, and thinks that these 

 observers have mistaken capillaries for lacteals. The lacteal he regards, on the contrary, 

 as originating by irregular channels formed by the interstices in the tissues of the villus. 



The commencement of the complete chyliferous vessels occurs in the deeper part of the 

 mucous membrane. In the submucous areolar tissue large vessels with distinct walls, and 

 furnished with valves and an epidielium, are observable. In the smaller ramifications 

 these cannot be detected; nor can a separate tunica propria of the walls be distinguished 

 from the areolar tissue which forms the adventitia. In the muscular layer the chyliferous 

 vessels have valves ; they are accompanied on each side by an artery and vein. In the 

 mucous and submucous tissue no such arrangement of the bloodvessels exists. 



The chyle, Professor Brucke asserts, does- not enter the vessels merely from the villi, but 

 also from between them, and principally from between the glands of Lieberkuhn, where it 

 may be observed lying free in the interstices of the tissue. This commencement of the 

 chyliferous vessels by open extremities in the interstices of the stroma of tissues, he regards 

 as sufficient to account for the circumstance, that absorption may take place in parts of the 

 intestinal canal not possessed of villi, as in the large intestine. The lymphatics, as well as 

 the chyliferous vessels, he considers to commence by channels in the tissues, and thus 

 the curious fact noticed by him {vid. " Denkschriften der Wien Acad.," vol. ii. p. 21), 

 that a colored solution may penetrate through the capsules of the Peyerian glands and reach 

 the thoracic duct, is readily explained. 



With regard to the anatomy of the chyliferous vessels after they leave the intestinal walls, 

 Brucke confirms the recent observations of Ludwig and Noll [vid. § 219, infra). The best 

 method to examine the commencements of the chyliferous vessels, is to allow the chyle 

 time to coagulate in the vessels, and then to render the walls of the intestine transparent. 

 This is most readily eflected by a solution of albumen in caustic potassa, to which enough 

 hydrochloric acid has been added to neutralize the alkali. 



In the animals he examined, Professor Briieke found the arrangement of the chyliferous 

 vessels to be in the main similar to that in Man. In the Weasel there is no difference. In 

 the Rabbit the chyle is not contained in separate channels, but is situated, throughout the 

 whole thickness of the intestinal wall, in the interstices between the sheaths of the blood- 

 vessels. In this animal, therefore, the chyle is separated from the blood merely by the 

 thickness of the membranes of the bloodvessels, whilst in Man this is the case only in the 

 mucous layer of the intestine. In the Pig, the walls of the chyliferous vessels exhibit a 

 distinct layer of muscular fibres. In the Mouse, the deposits of chyle in the interstices be- 

 tween the glands of Lieberkahn are readily seen. 



The contractions of the intestinal canal Brucke considers to be the principal means by 

 which the chyle is forced into the villi, these latter being kept erect and distended by the 

 pressure of the blood in their bloodvessels. As the chyle in the villi surrounds the blood- 

 vessels, a mutual interchange of some of the elements takes place ; the blood yields up fibrine 

 to the chyle, and the chyle a portion of its soluble parts to the blood. 



When the villi are filled, the contraction of their muscular fibres presses the chyle into 



