202 



EPITHELIAL GLOBULES. 



anatomical elements by an epithelial layer similar to the 

 endothelium of the blood-vessels (Fig. 61) : the continuation 

 of this layer shows that their function consists essentially in 

 properties of simple endosmosis or exosmosis ; their proximity 

 to the blood-vessels, and the sheath which in many parts they 

 form for these latter capillaries, may show, perhaps, that 

 their use is, not only to bring back to the blood those fluids 

 which are the products of destructive processes, as well as 

 those which have not yet been absorbed by the process of 

 nutrition ; but also to become filled with the excess of the 

 plasma of the blood, which enters these capillaries at each 

 systole of the ventricle (E. Onimus). 



Many histologists, however, assert that, before the network 

 of the capillaries is formed, or at the level of the most super- 

 ficial network, the origin of the lymphatic vessels consists of 



Fig. 61. Vascular epithelial cells f of the capillaries) Impregnated with nitrato 



of silver. 



simple Iacuna3 partially lined with an epithelium : in this 

 case, the real origin of the lymphatic vessels would consist 

 of the communications between these lacuna?, either with the 

 cells of the connective tissue, or with smaller lacuna?, the 

 network of the interstitial canaliculi of the connective tissue. 

 This view resembles greatly an ancient theory (Hunter, 

 Haase, etc.), according to which hypothesis these vessels 

 took their rise in radicles terminating in absorbing mouths or 

 pores, in the deep tissues as well as on the surface of the 

 serous and mucous membranes ; these opinions are now, 

 however, corroborated by experiments and histological re- 



