220 EXPERIMENTAL PHYSIOLOGY. 



tates insertion of the cannula. It should be remembered that the 

 lymph clots readily, and if this occurs in the neck of the cannula, 

 the clot will require to be broken up by means of a fine hair. The 

 cannula is connected by a short piece of flexible rubber tubing with a 

 bent glass tube, from the end of which the lymph is allowed to drop. 



A cannula is also inserted in the femoral vein and connected 

 with a burette. 



There are two types of experiment which may be demonstrated 

 on lymph flow. One of these concerns the stimulating effect of 

 certain chemical substances when injected into the general circula- 

 tion the lymphagogues and the other, the effect of alterations of 

 the circulatory conditions in the intestines and liver. 



The lymphagogues are of two classes, saline and colloid. To 

 illustrate the former a strong solution of glucose (20 per cent.) is 

 injected intravenously a few c.c. at a time until an increase in the 

 number of drops of lymph is produced. The amount of injection is 

 then increased. If the neck lymphatic flow is also being observed, 

 particular regard should be given as to whether it behaves similarly 

 to that of the thoracic duct. Repeat the experiment, using a 10 % 

 solution of sodium chloride. Explain the results. 



In the foregoing experiment it will be observed that the arterial 

 blood pressure either remains unaltered or rises slightly. To 

 illustrate the colloid lymphagogues, small quantities of a solution 

 of commercial peptone are injected. Note that besides affecting 

 the lymph flow there is a decided drop in arterial blood pressure. 

 (Care must be taken not to allow this to reach the danger limit). 

 Explain the result. 



Finally it may be shown that certain drugs and hormones also 

 act as lymphagogues. To illustrate this, pituitrin may be used 

 (1 c.c. for a dog of average size, 8 kgm.). 



The influence of circulatory changes in the splanchnic region 

 may be illustrated as follows: after opening the abdomen in the 

 linea alba a loose ligature is placed around the portal vein near 

 the hilus of the liver. When the normal rate of lymph 

 flow (from both ducts) has been ascertained the vein is closed by 

 pulling on the ligature; a decided increase in flow is observed. 

 If the ligature be tightened for long the lymph will become turgid 

 with blood. How do you explain the results? 



