510 ABSORPTION. 



empties into it, and fix in it a tube of appropriate size ; but 

 in dogs, the vessels are more deeply situated, and the opera- 

 tive procedure is much more tedious. This, however, is the 

 only way in which lymph and chyle can be obtained from 

 the lower animals in any considerable quantity. 



Quantity of Lymph. Although the experiments just 

 described might at first seem sufficient to give a pretty 

 clear idea of the entire quantity of lymph discharged into 

 the venous system, it is evident that the conditions of the 

 circulation of this fluid must be so seriously modified by the 

 establishment of a fistula, that the results thus obtained are 

 far from being entirely satisfactory. In the first place, Colin 

 found that the canal, at its junction with the subclavian 

 vein, was seldom single ; and in many of his observations in 

 which a very large quantity of liquid was obtained, there were 

 several vessels of nearly equal size emptying into the venous 

 system. In the experiment which we have referred to, how- 

 ever, the opening was single; and the quantity of fluid 

 obtained represented all that passed up the thoracic duct 

 during the time that the observation was continued. As 

 we should naturally expect, the discharge of liquid was 

 subject to certain variations, its maximum corresponding 

 with the period of greatest activity in digestion and ab- 

 sorption. 



It is not possible to estimate the influence of the unob- 

 structed discharge of lymph and chyle by a fistulous opening 

 upon the absolute quantity which passes out of the canal ; 

 and in the natural course of the circulation, there is a certain 

 amount of obstruction to ics entrance into the vein, which 

 might sensibly retard the current. 



According to the estimates of Dalton, deduced from his 

 own observations upon dogs and the experiments of Colin 

 upon horses, the total quantity of lymph and chyle produced 

 in the twenty-four hours in a man weighing one hundred 

 and forty pounds is from six to six and a half pounds. And, 



