PROPERTIES AND FORMATION OF LYMPH 241 



centration than normal lymph. It must be admitted, however, that 

 this change may be caused by a rapid influx of the ''blood plasma" 

 from the liver capillaries. 



The view of Heidenhain, that the lymphagogues exert their char- 

 acteristic action by stimulating the cells of the capillary walls to 

 greater activity, has been objected to by Starling, upon the ground that 

 the lymphagogues of the first class injure the lining cells of the blood- 

 vessels, and especially those of the liver. Hence they permit a greater 

 through flow of concentrated lymph simply by being more permeable. 

 The lymphagogues of the second group are said by him to render the 

 lymph hypertonic, thereby equipping it with a greater osmotic pres- 

 sure. In consequence of this change the tissue-fluid is drawn into the 

 larger lymphatics and eventually finds its way into the blood-stream. 

 Priority, however, cannot be accorded to this statement, because Hei- 

 denhain has shown at an even earlier date that the lymph-driving prop- 

 erties of these substances are proportional to their osmotic power. 

 Ascher^ and his pupils regard the lymphagogues of the first class as 

 liver-poisons which not only tend to increase the formation of lymph, 

 but also accelerate the other activities of this organ. Thus, it has 

 been demonstrated that chemical and morphological changes, such as a 

 disappearance of the glycogen, result whenever these substances are 

 injected. In a similar manner, Popoff^ has shown that the introduc- 

 tion of peptone increases the flow of lymph from the thoracic duct, but 

 does not augment the flow from other channels. This result is easily 

 explained, because this extra quantity of lymph is derived principally 

 from the intestine. It has also been noted that the peptone gives rise 

 to a hyperemic condition of the pOrtal blood-vessels which eventually, 

 culminates in hemorrhagic extravasations into the intestinal wall. 



As the average student of physiology is largely concerned with the 

 acquisition of definite fundamental facts and cannot be expected to 

 display a keen interest in controversial discussions, it seems best not 

 to debate this question further. Suffice to say, that we are in posses- 

 sion of certain agents which give rise to a greater formation of lymph 

 without causing significant alterations in either the general or the local 

 blood pressure. Clearly, if the dynamical conditions in the capillaries 

 are permitted to remain the same, while at the same time a more 

 copious discharge of lymph is obtained, it may justly be assumed that 

 this result is dependent upon a greater activity of the lining cells of the 

 capillaries. In accordance with the conception of Heidenhain, these 

 cells may therefore be said to be equipped with true secretory powers. 

 But even if the reader should feel inclined to favor the view that these 

 phenomena do not necessitate the assumption of a vital activity on the 

 part of the lining cells, the filtration theory would nevertheless have 

 to be greatly modified, because we are still in a position to cite other 

 data in opposition to it. 



^ Zeitschr. fiir Biologie, xxxii-xlvii, 1895-1906. 

 2 Jour, of Physiol., xxv, 1899, 479. 

 16 



