4 i8 SCIENCE PROGRESS. 



this amount, it follows that the intra-capillary pressure 

 will be proportional to the same quantity, and thus all the 

 facts can be explained by the filtration hypothesis. 



Members of the first class of lymphagogues act injuri- 

 ously on the endothelial cells of the capillaries, especially 

 in the liver, increasing their permeability ; and also on the 

 muscular walls of the blood-vessels, especially in the splanch- 

 nic area, producing vascular dilatation, and thirdly on the 

 heart muscle ; the increased Mow of lymph is thus not a 

 physiological but a pathological occurrence, and is due to the 

 increased permeability of the hepatic capillaries, nearly all 

 of the increased lymph flow being derived from the liver. 



It will be remembered that Heidenhain stated that, after 

 long-continued obstruction of the aorta, the first class of 

 lymphagogues no longer produce an increased lymph flow. 

 This Starling finds is perfectly true ; but obstruction of the 

 aorta is a very serious proceeding ; it causes extreme 

 injury to the vessel walls, such that when the aorta is again 

 released the pressure in the portal vein rises very slowly, 

 and the intestines are found full of a yellow pasty mass, 

 consisting of desquamated epithelium cells ; in fact there iv 

 here an exquisite example of Cohnheim's experiment in the 

 production of inflammation by anaemia. Thus it is evident 

 why injection of these lymphagogues has no effect after 

 obstruction of the aorta. The endothelium of the vessels is 

 so damaged that it is as impossible to alter its permeability 

 as it would be to kill a dead dog ; though, of course, by 

 injection of sugar or any other lymphagogue of the second 

 class the osmotic phenomena still occur, which lead to an 

 increased formation of lymph. 



These are the main points in connection with this 

 subject. I have endeavoured to present both sides im- 

 partially, and shall not attempt to pronounce which has, in 

 my opinion, the best of the argument. It would indeed be 

 premature to pronounce judgment at present. Heidenhain 

 has not replied to his critics, and we have not, I imagine, 

 heard the last word on the subject by a long way. Indeed, 

 Starling confesses that on one point his position is in- 

 complete, and this is the very point which to me has always 

 seemed the strongest argument in favour of Heidenhain's 

 views. That is that after injection of sugar, etc., the 

 percentage amount of these substances in the lymph from 

 the thoracic duct rises higher than that in the blood plasma. 

 But as another paper is promised on this subject it would 

 be better to leave the matter as it stands for the present. 



W. D. Halliburton. 



