8 SAMUEL JAMES MELTZER— HOWELL [MEM0,M [$£xx^ 



superior cervical ganglion is first excised, then, after a certain interval, subcutaneous injections 

 bring on a marked and long-lasting dilatation. His explanation of these phenomena was made 

 in terms of his theory of inhibition. Whether or not his views in regard to the relations of the 

 cervical ganglion to pupillary dilatation will stand the test of future experimental work, it is 

 to be noted that the observation itself constitutes a significant instance of a kind of independent 

 physiological activity on the part of a peripheral ganglion. The bearing of these facts upon 

 the prevalent conception of the rapid destruction of epinephrin in the tissues was brought out 

 especially in a paper with Auer, in which it was shown that if adrenalin is injected into a ligated 

 limb and an hour or so afterward the ligature is removed the dilatation of the pupil quickly 

 follows, thus demonstrating that for this long period the adrenalin had remained unaffected 

 by the tissues. It is interesting to note that he made a second confirmatory contribution to 

 this phase of the adrenalin effect in the last year of his life, in work done again with Auer and 

 not published until after his death. Two incidental results that came out of this series of 

 experiments have proved to be of value in physiological work. One was the discovery that the 

 isolated eye of the frog shows dilatation of the pupil when exposed to small concentrations of 

 adrenalin. A convenient biological reagent was thus furnished for the detection of minute 

 amounts of adrenalin in the body liquids. The other was the fact that absorption takes place 

 much more rapidly in intramuscular than in subcutaneous injections. The marked physiological 

 effects of adrenalin furnished a positive indication of the rapidity of absorption, and the discovery 

 that injections made intramuscularly are absorbed with great promptness has since been utilized 

 to advantage by other workers. 



The work upon the inhibitory and anesthetic effects of magnesium salts gave rise to no less 

 than 25 papers, most of them published in collaboration with one or another of his associates, 

 but chiefly with Doctor Auer. The peculiar inhibitory action of magnesium sulphate had 

 attracted his attention as far back as 1899, and he reported upon it incidentally in a communi- 

 cation to the American Physiological Society. But in 1904-5, influenced again by his general 

 conception of the importance of the inhibitory processes, he took up with Auer a careful physio- 

 logical study of its action. The results were most interesting and important. When given 

 subcutaneously in certain doses the magnesium sulphate produces a condition of complete 

 unconsciousness and muscular paralysis or relaxation, which is reversible, in the sense that when 

 the animal is given proper care it recovers. Later he was able to show that out of this condition 

 of profound depression or inhibition the animal may be restored to complete consciousness 

 and motility with miraculous suddenness by the intravascular injection of small amounts of 

 calcium chloride. No one who was fortunate enough to see this demonstration as given by 

 Doctor Meltzer will forget its dramatic effect upon his audience. A healthy vigorous rabbit 

 was brought quickly to a condition of complete immobility and apparent death by the magnesium 

 sulphate and then even more suddenly raised from the dead and restored to its normal tranquil 

 existence by the injection of some calcium chloride. Meltzer and his collaborators investigated 

 various phases of this action of magnesium sulphate, and all of the results obtained tended to 

 strengthen in his mind the conviction that in magnesium he had discovered the element in the 

 body that is especially concerned in the processes of inhibition. The antagonistic action of 

 the calcium, although exhibited in such a striking way, was not in his opinion specific. His 

 own experiments in connection with the results reported by other observers led him to the general 

 view that calcium serves to balance the abnormal activity of the other kations, potassium, 

 sodium, and magnesium, whether this abnormal action is in the direction of excitation or of 

 inhibition. Modern work upon the physiological significance of the inorganic constituents of 

 the body fluids which was begun in Ludwig's laboratory, but was given its main impetus by the 

 striking contributions of Ringer, had concerned itself chiefly with the salts of potassium, sodium, 

 and calcium, which alone seemed to be sufficient to maintain normal conditions of irritability. 

 Meltzer's work has shown that magnesium also has its place in this ancient balance of powers 

 through which the functional activity of protoplasm is controlled. One can understand that 

 in arriving at thees results he must have felt that he was approximating at least a demonstration 

 of the correctness of his general conception of the role of inhibition in functional activity. In this, 



