134 MANUAL OF HISTOLOGY. 



and the colourless fluid found in its vessels which has been strained 

 off from the blood -capillaries, as " lymph" 



Now the latter, although it may appear pretty much the same to the 

 observer's eye in the various regions of the body, cannot possibly have 

 identically the same composition everywhere from what we have just seen 

 above. On the contrary, it will always be found to differ according to 

 the nature of the tissue or organ from which it flows, and to be, there- 

 fore, a fluid of more variable constitution than the streams of blood 

 belonging to the several regions of the circulatory system. 



There is, however, in our body one portion of the lymphatic system which 

 serves other purposes, at least, at certain times. The lymphatic canals 

 namely, of the intestinal mucous membrane contain in the fasting state a 

 fluid possessing all the usual characteristics of lymph. During digestion, 

 however, there enters by the radicals of this system of canals a mixture of 

 albuminous substances and fats taken up from the alimentary matters. We 

 now find the passages charged with a whitish, opaque, and frequently milky 

 fluid, to which, owing to its appearance, the name "milk-juice" or "chyle" 

 has been given. These particular vessels are then spoken of as lacteals. 



83. 



Both these juices contain, suspended in a plasma or fluid intercellular 

 substance, a considerable number of cells all possessing the same nature 

 (lymphoid cells) ; these are known, from the mode of their occurrence, as 

 lymph and chyle corpuscles. They were first discovered by Leeuwenhoek 

 and Mascagni. 



In all essential particulars they correspond with the colourless cells of 

 the blood, already discussed at ( 69) ; nay more, they are identical with 

 them. The cells of the lymph and chyle, namely, pass into the blood, 

 and circulate there as white corpuscles. Besides these, there are other 

 immeasurably small molecules to be seen, especially in the chyle, as also 

 larger elementary granules, while in some particular regions, especially of 

 the lymphatic system, isolated red blood-cells may be observed. 



The ceils in both fluids display much variety as to size and other 

 relations, and no regular law seems to govern their distribution, although 

 one or other form of cell may at times gain the ascendancy in this or 



that region. It is a fact of great interest, 

 farther, and one which may be especially 

 clearly recognised in the chyle absorbents, 

 that either none at all, or very few of these 

 corpuscles are to be seen in the finest 



\~ ^~ , radicals, when on the point of leaving the 



/>) (K) (^f wall of the intestine; but that they be- 

 V s ' ^< \^J come all at once very numerous in the 

 fluid after the passage of the latter through 

 and the mesenteric glands. The same may be 



id a e: bSei>Ved in tlier P <dI>tS f the ^P^ 

 as also at 10 and 11 ; at 12 it has sepa- System. 



i?be?atu 8 cfei pieces; at 13 we have Now as to the cells themselves, more 



particularly, they may be said to have been 



already considered when speaking of the blood. They are the same for- 

 mations, namely, with like diversity as to size, as to the body of the cell 

 and its contents, with the same kind of nuclei and endowed with the 

 like vital contractility as the colourless corpuscles of that fluid. 





