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SCIENCE 



[N. S. Vol. XLIV. No. 1136 



is still some difference of opinion. For- 

 merly it was localized in the terminations of 

 the nervous fibers in the muscle and ganglia, 

 but Langley has shown that in the latter 

 the point of action lies in the ganglion-cell 

 itself, and his researches on the antagonism 

 of nicotine and curare in muscle appear to 

 show that the reacting substance lies more 

 peripherally than was supposed, perhaps 

 midway between the anatomical termination 

 of the nerve and the actual contractile sub- 

 stance. Another analogy in reaction has 

 been shown to exist between the ganglia and 

 the terminations of the post-ganglionic 

 fibers of the parasympathetic, for Marshall 

 and Dale have pointed out that a series of 

 substances, such as tetramethyl-ammonium, 

 affect each of these in varying degrees of 

 intensity. The specific character of the re- 

 action is shown by the fact that while it is 

 possessed by the tetramethyl-ammonium 

 salts, the tetraethyl-ammonium homologues 

 are entirely devoid of it. 



Another close relationship is shown by 

 the reaction of the glucosides of the digitalis 

 series on the heart and vessels. These all 

 act on the muscle of the heart, and in higher 

 concentration on that of the vessel-walls. 

 There must therefore be a common base in 

 these which is affected by the drugs. And 

 the existence of this is perfectly intelligible 

 in view of the fact that the heart is devel- 

 oped from the vessels. A more obscure 

 relationship is shown by the reaction of this 

 group to the inhibitory cardiac center in 

 the medulla, which is thrown into abnor- 

 mal activity by their presence in the blood, 

 as has been shown alike by clinical and ex- 

 perimental observations. A similar relation 

 is shown by the common reaction of the 

 heart-muscle and the vagus center to aconi- 

 tine and some other related alkaloids. On 

 the other hand, the saponin series, which 

 shows a closer relationship to the digitalis 

 bodies in the heart-muscle, is devoid of its 



characteristic action on the medulla. The 

 reacting substance in the heart is thus 

 capable of responding to digitalis, saponin 

 and aconitine, while that in the vagus cen- 

 ter can associate only the first and last and 

 is not affected by the saponins ; the common 

 reactions indicate that the two are related, 

 while the distinctive effect of saponin shows 

 that they are not identical. A similar rela- 

 tionship may be drawn from the action of 

 morphine and the other opium alkaloids on 

 pain sensation, on respiration, and on the 

 movements of the alimentary tract. Exact 

 determinations of the relative power of 

 these alkaloids in these regions are not at 

 our disposal as yet, but sufficient is known 

 to suggest that while morphine affects a 

 common substance in the medullary center 

 and the intestinal wall, the other members 

 of the series act more strongly in one or 

 other position. 



It was long ago pointed out that caffeine 

 affects both kidney and muscle-cell, and 

 Schmiedeberg has attempted to correlate 

 the intensity of action of the purine bodies 

 at these points and to measure the prob- 

 able diuretic action by the actually ob- 

 served effect on the contraction of muscle. 

 Other reactions of the kidney suggest a rela- 

 tionship to the wall of the bowel. For ex- 

 ample, many of the heavy metals and some 

 other irritant bodies act strongly on the 

 kidney and bowel, and again, according to 

 one view of renal function, many of the 

 simple salts of the alkalies affect the kidney 

 in exactly the same way as the bowel-wall. 

 This last may, however, be due to the phys- 

 ical properties of the salts, and the likeness 

 in reaction to those of kidney and bowel, 

 which is striking enough, may arise from a 

 likeness in function of the epithelium rather 

 than from any specific relationship to the 

 salts which is not common to other forms of 

 living matter. 



