STOMATA OF THE CAPILLARY LYMPHATICS. 307 



foramina. Up to a recent period it has been generally accepted 

 that epithelial investments, except in the case of glandular 

 epithelium, serve as a protection to the subjacent tissues, and 

 therefore, by the intimate union of the cells with each other, 

 form a firm, close tissue, permeable only for fluids. Since, 

 however, the terminal apparatus of the sensory nerves has been 

 discovered in the epithelial strata, and very recently also 

 cup-shaped organs, both of which seem to be but ill adapted 

 for protection, the epithelial tissues have gradually attracted 

 more and more attention from histologists, and it is not sur- 

 prising that further inquiries should be undertaken with the 

 view of discovering other and peculiar arrangements. It is 

 reasonable, therefore, on db priori grounds, to concede that the 

 epithelial coating of chyle and lymphatic capillaries may pre- 

 sent special peculiarities which stand in relation to the absorp- 

 tion of material from the surrounding tissues, and may, at any 

 rate, at certain times, facilitate their passage. In some lym- 

 phatics, openings of appreciable size are already known to occur, 

 through which, even during life, small bodies may be absorbed 

 into the interior of the tube. They were first demonstrated 

 by Recklinghausen, in the central tendon of the diaphragm. 

 If we inject into the peritoneal cavity of mammals milk, 

 blood, or fluids which have insoluble substances (consequently 

 not carmine) in suspension, a beautiful injection of the net- 

 work of lymphatics of the central tendon of the diaphragm 

 may be obtained. If we press a cork ring against the central 

 tendon from the thoracic side, attach a portion to it with 

 needles, and then excise it, we are enabled to procure the 

 surface of the tendon in an absolutely uninjured state. If now 

 we place a drop of milk upon this, the absorption of milk 

 globules into the lymphatic vessels may be directly observed 

 under the microscope. The milk globules run towards certain 

 points at which small vortices occur whilst they are penetrating 

 into the subjacent lymphatics. The openings through which they 

 gain entrance are only wide enough to admit two or three milk 

 globules abreast, are roundish, sometimes even quite round, 

 and represent, as is clearly shown by subsequent staining with 

 nitrate of silver, spaces between the epithelial cells. They usually 

 lead perpendicularly into the lymphatic vessels, over which they 



