CHAP. V.] 



PHYSICAL CHARACTERS OF LYMPH. 



221 



Chyle is the 

 term applied 

 to the lymph 

 contained in 

 the lympha- 

 tics of the 

 small intes- 

 tine during 

 digestion. 



quantity of 

 Lymph and 

 Chyle. 



Whilst the lymphatics generally contain a liquid 

 which must be looked upon as a diluted liquor sanguinis, 

 deprived of a small fraction of certain of its constituents, 

 and augmented by certain other constituents, such as 

 urea or carbonic acid, which are the effete products of 

 tissue metabolism, certain of the lymphatics those of 

 the small intestine contain, during the period of diges- 

 tion, lymph which is laden with suspended fattymatter in 

 a fine state of division, and which gives to the fluid a milky appear- 

 ance. The fatty matter has passed from the interior of the alimentary 

 canal through, or between, the cylindrical epithelial cells of the villi 

 into the sub-epithelial connective tissue, whence it has made its 

 way into the commencements of the so-called lacteals, as the ab- 

 sorbents of the intestinal villi are called. Chyle is therefore the 

 lymph of the small intestine laden with fat whilst the absorption of 

 that substance is proceeding. The Chyle will be considered in detail 

 in relation to the functions of Digestion and Assimilation. 



Circum- The amount of lymph which is discharged by the 



stances which lymphatics of a part is much increased by muscular 

 influence the J ,. . , , J . , TT1 



contractions and passive movements 01 the part. When 



the arterial pressure is increased the amount of lymph 

 diminishes. When an obstruction to venous circulation 

 exists the amount of lymph increases. Poisoning with curare increases 

 the discharge of lymph. The amount of chyle is materially increased 

 by the digestion of food rich in fatty matters. 



Mode of Small quantities of lymph for microscopic exami- 



obtaining nation may be obtained by puncturing the subcutaneous 



Lymph. dorsal lymph-sac of the frog, and aspirating with a 



capillary pipette. 



When large quantities of lymph are required they may be obtained 

 by tying a glass cannula into the thoracic duct of a deeply anaesthe- 

 tized animal, at the spot where that tube empties itself into the 

 junction of the large veins at the root of the neck 1 . 



In large animals, such as the horse and ox, a cannula may be 

 tied into one of the large cervical lymphatics accompanying the 

 rotid artery. 



For purposes of demonstration small quantities of lymph may 

 be obtained from the thoracic duct of a recently killed animal. 



Physical characters of the Lymph. 



When freshly drawn from the thoracic duct of fasting 

 animals the lymph is a transparent liquid, sometimes of 

 a slight yellow colour; when obtained from an animal 

 during the period of digestion, it presents a more or less milky colour 

 owing to the absorption of fatty matters from the alimentary canal. 



1 This method was followed by Dogiel and by Hammarsten, in their researches on the 

 gases of lymph, conducted in the Leipzig Laboratory under the direction of Professor 

 Ludwig. (See ' Gases of Lymph, ' p. 225.) 



Colour, and 

 microscopic 

 characters. 



