242 THE LYMPH 



It is a well-known fact that the stimulation of the choida tympani 

 nerve is folio wed by a dilatation of the blood-vessels of the submaxillary 

 gland and a copious discharge of saliva. This effect is not obtained 

 subsequent to the administration of atropin. Concerning the dis- 

 charge of lymph, it has been found by Heidenhain and Cohnheim 1 

 that the excitation of this nerve causes no alteration, in spite of the 

 fact that the vascularity of this organ is very much increased. Fur- 

 thermore, it has been observed by Barcroft 2 that the water lost by the 

 blood during its passage through this gland, enters not only the 

 salivary ducts, but also finds its way in even greater quantities into 

 the lymphatics. In this connection, it should also be mentioned that 

 Ascher and his co-workers have proved that other organs, such as the 

 thyroids, intestine, liver, and pancreas, give rise to much greater 

 amounts of lymph whenever their activity is heightened, and that the 

 lymph formed during these periods of increased metabolism is more 

 concentrated. In explanation of these phenomena it is possible to 

 submit three views, namely, (a) that any glandular activity leads to 

 the production of certain substances which tend to stimulate the lining 

 cells of the capillaries (Heidenhain), (6) that lymph may also be formed 

 by the secretory cells of these glands (Ascher), and (c) that the complex 

 molecules of the proteins, fats and carbohydrates are simplified so that 

 the number of the particles in solution in the lymph is increased in 

 harmony with the increase in the osmotic pressure of the latter 

 (Starling). 



The third view has also been offered by Starling and others in 

 explanation of the fact that the intravascular lymph and tissue-fluid 

 possess a greater molecular concentration than the blood. 3 As has 

 been stated previously, it is believed that the disintegration of the 

 complex molecules renders the lymph hypertonic and that this cata- 

 bolic change then leads to an influx of water into the lymphatics. 

 On close examination, however, this explanation cannot be considered 

 as a very good one, because it is known that the vascular walls are 

 very permeable to water, and hence, it seems quite unlikely that the 

 osmotic differences between the blood and the tissues can be main- 

 tained for any length of tune. For this reason, it is safe to assume 

 that the greater molecular concentration of the lymph can only be 

 retained with the aid of some special activity of the lining cells of 

 the capillaries. 



In this connection, mention should also be made of the experiments 

 of Heinecke and Megerstein 4 which show that the sodium chlorid 

 content of the blood-serum of nephritic rabbits is less than that of the 

 ascitic fluid. Moreover, if this salt is ingested in larger amounts, the 

 percentage of this salt increases in the serum as well as in the transu- 



1 Vorles. uber allg. Pathologie, 2, Ausgabe, i, 1882, 493. 



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



3 Botazzi, Ergebn. der Physiol., vii, 1908, 310. 



4 Archiv fur klin. Med., xc, 1907, 101. 



