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SCIENCE 



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



poisons is the ferments, and quinine and 

 prussie acid may therefore he regarded as 

 qualitative tests for the presence of some 

 ferments, notably those of oxidation, and, 

 in fact, have been used to determine 

 whether a change is fermentative in char- 

 acter or not. Formaldehyde was stated by 

 Loew to be poisonous to living matter 

 through its great affinity for the NH„ group 

 in the proteins, a suggestion which has per- 

 haps not received enough attention of late 

 years, during which the importance of this 

 group in proteins has been demonstrated. 

 The toxicity of other general poisons, such 

 as cocaine, is more obscure. But what has 

 been gained already in this direction en- 

 courages further investigation of the action 

 of the so-called general protoplasm poisons 

 and further efforts to associate it with the 

 special constituents of the cell. 



In other poisons the action on the central 

 nervous system is the dominating feature, 

 and among these the most interesting group 

 is that of the simple bodies used as an- 

 esthetics and hypnotics, such as ether, 

 chloroform and chloral. The important 

 use of this group in practical medicine has 

 perhaps obscured the fact that they act on 

 other tissues besides the central nervous 

 system, though we are reminded of it at too 

 frequent intervals by accidents from an- 

 esthesia. But while they possess this gen- 

 eral action, that on the nervous tissues is 

 elicited more readily. Not only the nerve- 

 cell, hut also the nerve-fiber react to these 

 poisons, as has been shown by Waller and 

 others. And even the terminations are 

 more susceptible than the tissues in which 

 they are embedded, according to the ob- 

 servations of Gros. The selective action on 

 the nervous tissues of this group of sub- 

 stances has been ascribed by Overton and 

 Meyer to the richness in lipoid substances 

 in the neurons, which leads to the accumu- 

 lation of these poisons in them, while cells 



containing a lower proportion of lipoid are 

 less affected. In other words, Overton and 

 Meyer regard these drugs as a means of 

 measuring the proportion of lipoids in the 

 living cell. This very interesting view has 

 been the subject of much discussion in re- 

 cent years, and, in spite of the support 

 given it by several ingenious series of ex- 

 periments by Meyer and his associates, no 

 longer receives general acceptance. Too 

 many exceptions to the rule have to be ex- 

 plained before the action of these bodies 

 can be attributed wholly to their coefficients 

 of partition between lipoids and water. At 

 the same time the evidence is sufficient to 

 justify the statement that the property of 

 leaving water for lipoid is an important 

 factor in the action of the bodies, although 

 other unknown properties are also involved 

 in it. And whatever the mechanism of the 

 characteristic action, these substances in 

 certain concentrations may be regarded as 

 tests for the presence of nervous structures 

 and have been employed for this purpose. 



Other bodies acting on the nervous sys- 

 tem have a much narrower sphere. Mor- 

 phine and strychnine, for example, appear 

 to be limited to the region of the nerve-cells, 

 but there is still doubt whether they affect 

 the cell-body alone or the synapses between 

 certain of its processes. They have not 

 been shown to act on peripheral nervous 

 structures in vertebrates, nor on any but 

 specific regions of the central nervous sys- 

 tem. Nor has it been established that they 

 affect invertebrates. The substance with 

 which they react is obviously limited by 

 very narrow boundaries around the nerve- 

 cell. 



More interest has been displayed in re- 

 cent years in the alkaloids which act on the 

 extreme terminations of various groups of 

 nerves. These are among the most specific 

 reagents for certain forms of living matter 

 which we possess. Thus, if an organ reacts 



