BY DR. BURDON-SANDERSON. 297 



is thought by Goltz, 1 the author of this experiment, to indicate 

 that when a sensory nerve is excited, venous absorption is in- 

 creased. It may perhaps be attributable rather to the contrac- 

 tion of the vessels which is determined by the excitation. To 

 render the observation of the result as accurate as possible, 

 the quantity discharged should be measured. The quantity 

 found in the test-glass in which the mixture of blood and serum 

 is collected should, together with the residue remaining in the 

 lymph sac, be equal to the quantity originally injected. In 

 the other frog there is no discharge. The heart remains flaccid 

 although contracting regularly, and the skin dry from the arrest 

 of the secretion of the cutaneous glands. In this experiment 

 it may be supposed, either that the liquid contained in the 

 lymph sac passes into the circulation directly, or that it first 

 diffuses out into the surrounding tissue, and is then absorbed 

 by the veins. The first supposition is negatived by the obser- 

 vation that the contractions of the lymph hearts have ceased 

 in both frogs, and that consequently the mechanism by which 

 alone the liquid could be directly transferred to the venous 

 system is wanting. We are, therefore, compelled to admit that 

 it enters the blood-stream by the only other channel open to 

 it ; and the conditions of the experiment prove that it does so 

 under the direct influence of the nervous system. 



The precise nature of the agency by which the living ele- 

 ments which surround the bloodvessels determine the diffusion 

 of liquid into the blood in opposition to pressure, cannot at 

 present be stated. In the instance before us, two sets of effects 

 may be distinguished as referable to one cause, i. e., destruc- 

 tion of the central nervous system those due to paralytic 

 relaxation of the bloodvessels, and those which are attributable 

 to absence of absorption. In how far those of the second 

 kind are the immediate result of the others, may perhaps be 

 open to question. They do not, however, afford any explana- 

 tion of them, for there is no reason why a relaxed vessel 

 should not absorb quite as much as a contracted one ; the fact 

 of relaxation affords no explanation whatever of the absence 

 of absorption. Both are manifestations of properties enjoyed 

 by the living elements only so long as they are in communica- 

 tion with cerebro-spinal nervous centres. 



1 " Ueber den Einfluss der Nervencentren auf die Aufsangung," 

 Pfliigers Archiv. B. v. p. 53. 



