BY DR. BURDON-SANDERSON. 295 



the lymphatic trunks are subjected to a less pressure than their 

 absorbing orifices, does not need special experimental proof. 

 Thus, for example, it is certain that the tymphatics of the peri- 

 tonaeum enter the thorax, i. e., pass from a cavity where the 

 pressure is usually greater, to another where it is much less 

 than that of the atmosphere. The influence of muscular move- 

 ments admits of being demonstrated by the following experi- 

 ment, which at the same time affords a striking confirmation 

 of the evidence already given as to the mechanical nature of 

 lymphatic absorption. 



In a large dog, which has been just killed by opening one 

 carotid, the skin, costal cartilages, and muscles of the flank are 

 severed by a transverse incision, which extends from the ensi- 

 form cartilage as far as the middle line on either side. The 

 wall of the abdomen is then split vertically in the linea alba, 

 and the diaphragm cut away from the ribs. The bladder hav- 

 ing been squeezed empty, two ligatures are tightened round 

 the rectum, which is divided between them. Ligatures must 

 now be placed round the cardia, the hepatic vessels, and duct, 

 and the mesentery, so as to remove the stomach and intestines 

 en manse without bleeding. This having been accomplished, 

 the vena cava is tied above and below the liver, and that organ 

 removed, after which the body is bisected by sawing through 

 the eighth vertebra, and completing the division of the soft 

 parts. Finally, a glass canula, fitted with a flexible tube 

 guarded by a clip, is inserted in the thoracic duct and secured 

 with a ligature. 



If now the spinal column is fixed near the edge of the table, 

 and the lower limbs alternately flexed and extended by an as- 

 sistant, the lymph flows freely and may be received in a test 

 tube. If the passive movement is discontinued and then re- 

 sumed from time to time, the quantity of lymph collected is very 

 considerable, so that it is easy to fill several test tubes; but 

 none is discharged during the intervals of cessation. The lymph 

 which is collected at first, resembles ordinary lymph both in 

 its microscopical characters and in its composition. It is ob- 

 vious that it is the liquid which at the moment of death occu- 

 pied the canaliculi of the tissues from which it is gathered. 

 The course taken by the lymph stream can be further demon- 

 strated in the same preparation, by introducing solution of 

 alkanet, by puncture, into the intertendinous splits of the 

 lower part of the fascia lata. If a sufficiently fine syringe is 

 used, it is easy to produce in this way a satisfactory injection, 

 first, of the lymphatic capillaries contained in the splits them- 

 selves, and secondly (if the passive movements are continued), 

 of the rich net-work of lymphatics which exists in the " cellular 

 membrane" which covers the aponeurosis on its cutaneous 



