SECT. 221. J THE BLOOD. 5 I 7 



intestine at least, to the glandular follicles of this part, the solitary 

 glands and the glands of Peyer : in favour of this helief may be 

 stated the circumstance observed by myself, that the chyle-vessels 

 coining from Peyer s patches arc more abundantly provided with 

 cells. Lymphatic vessels which have no connexion with glands, 

 either contain no cells at all, according to my observations (lym- 

 phatics of dog's liver and tadpole's tail), or only a very few, 

 as the lymphatics of the spermatic cord of the ox, and those of 

 the surface of the spleen. In such cases as the last, unless we are 

 content to believe in a free production of cells, a hypothesis which 

 has been shown in the general part of this work to be untenable, 

 we can only regard the scanty lymph-corpuscles as being the 

 epithelial cells of the smaller vessels, which give rise to the ap- 

 pearance of morphological elements in the lymph, either by a 

 normal multiplication or by an accidental partition of their cells. 

 A similar process of formation of lymph-corpuscles must explain 

 the multiplication of the cells, which is occasionally witnessed in the 

 lymphatic vessels between the glands and the thoracic duct. The 

 entire mass of corpuscles existing in the lymph, compared with that 

 of the blood-corpuscles in the blood, is very inconsiderable; not only 

 in the medium-sized and smaller trunks of the lymphatic vessels, 

 but even in the thoracic duct their numbers do not approach in 

 the remotest degree to those of the blood, as even in this situation 

 all the elements of the lymph can be inspected without dilution. 

 Accurate enumerations have, however, not yet been made ; and it 

 can only be stated, that here, too, a considerable variation exists, 

 and that a milk-white chyle is not always rich in corpuscles. 



§ 22i. Of the Blood. — The blood, so long as it circulates in the 

 vessels, is a slightly glutinous fluid in which only two elements 

 are to be distinguished, the blood-corpuscles, blood -globules, or 

 blood-cells, chiefly red but partly colourless (corpuscula s. glohuli 

 s. cellulce sanguinis), and the colourless fluid portion, the liquor 

 s. plasma sanguinis. After it has left the circulation, the blood 

 generally coagulates completely by the solidification of the fibrine 

 dissolved in its plasma, and afterwards separates by the contrac- 

 tion of the coagulated fibrine into a solid and liquid portion, 

 the crassamentum and the serum. The former is intensely red, 

 and contains, besides the fibrine, almost all the coloured, and the 

 majority of the colourless blood-globules, with some of the con- 

 stituents of the plasma which remain in solution ; while the 

 remainder of this plasma, together with some colourless blood- 



