54 HISTOLOGY O/< NUTRIENT FLUIDS. 



subarachnoid spaces of the central nervous system, the syno- 

 vial cavities, the cavities of the tendon sheaths, of the tunica 

 vaginalis testis, as well as the larger pleural, pericardial, and 

 peritoneal cavities, communicate with lymphatics, and form a 

 continuous system connected with the circulation of nutrient 

 fluid. The cavities above named connect with the neighbor- 

 ing lymphatic vessels by means of holes, orstomata, which are 

 often lined by a layer of polyhedral endothelial cells, called 

 germinating cells, producing leucocytes by their proliferation, 

 which are carried by the lymphatics into the system as white 

 blood corpuscles. Fig. i, PI. 3. 



5. Continuity of blood fluid. From the brief outline given 

 it will be seen that the true circulation of the blood is not 

 confined to the arteries, veins and capillaries, but involves a 

 complicate system of blood vessels, lymphatics, lacteals, large 

 cavities and interstitial spaces. In all this system we find the 

 real blood the fluid portion carrying in one part milky fluid, 

 or chyle, in another white cells, or leucocytes, and in another 

 both red and white corpuscles. 



The fluid of the blood is called plasma, scrum or liquor saii- 

 guinis. It is the conveyer of nutriment as well as of effete mat- 

 ter or pathological products. It is a germicide in its normal 

 state, and hence a protection against zymotic diseases. In a 

 case of leukaemia I have known it to dissolve red corpuscles, 

 which again acquired resisting power by the use of ferrum et 

 manganese iodidum. This example illustrates the importance 

 of its study. 



I 



II. LYMPH AND CHYLE. 



The term chyle is given to the milky juice, or emulsion, 

 with which the lacteals are filled during digestion. Its color is 

 due to fat, partially saponified with soda. It contains, also, 

 chloride of sodium. Its milky appearance is shown by the 

 microscope to depend upon very minute fatty granules sus- 

 pended in the fluid. Varying numbers of leucocytes are also 

 found in it. Lymph, or the fluid contents of lymphatics, is a 

 more or less alkaline, watery fluid. Both lymph and chyle are 

 similar to the serum, or fluid part of theblood, and, like it, con- 



