TRERTDENTTAL ADDRESS. 47 1 



that is, through the study of the pharmacology of these tissues. A simple 

 example may render the point clearer : It is possible that, if the toxicity of the 

 saponins to different cells were accurately known, the relative importance of 

 the lecithins in the life of these cells might be estimated, and this might give 

 a hint to the chemist in approaching their analysis. I do not claim that pharma- 

 cological investigation can at present do much more than the qualitative testing 

 of the tyro in the chemical laboratory, but even a small advance in the chemistry 

 of living matter is worthy of more attention than this has received hitherto. 



All forms of living matter to which they have free access are affected by 

 certain poisons, and some of these have obvious chemical properties which sug- 

 gest the method of their action ; thus the effects of alkalies and acids and of 

 protein precipitants hardly need discussion. Others, such as quinine and prussic 

 acid, which also affect most living tissues, have a more subtle action. Here it is 

 believed that the common factor in living matter which is changed by these 

 poisons is the ferments, and quinine and prussic acid may therefore be regarded 

 as qualitative tests for the presence of some ferments, notably those of oxida- 

 tion, and, in fact, have been used to determine whether a change is fermenta- 

 tive in character or not. Formaldehyde was stated by Loew to be poisonous to 

 living matter through its great affinity for the NH.^ gi-oup in the proteins, a 

 suggestion which has perhaps not received enough attention of late years, 

 during which the importance of this group in proteins has been demonstrated. 

 The toxicity of otiier general poi-sons, such as cocaine, is more obscure. But 

 what has been gained alrea<ly in this direction encourages 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. 



Tn 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 anaesthetics 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 l)y accidents from aUcTsthesia. But 

 while they possess this general action, that on the nervous tissues is elicited more 

 readily. Not only the nerve-eel], but also the nerve-fibre, 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 

 observations of Gros. The selective action on the nervous tissues of this group 

 of substances has been ascribed by Overton and jNIeyer to the richness in lipoid 

 substances in the neurons, which leads to the accumulation 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 recent years, and, in spite of the support 

 given it by several ingenious series of experiments by Meyer and his associates, 

 no longer receives general acceptance. Too many exceptions to the rule have to 

 be explained 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 luiknown 

 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 system have a much narrower sphere. 

 Morphine 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-l>ody 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 system. Nor has it been established that they affect 

 invertebrates. The substance with which they react is obviously limited by 

 very narrow bodndaries around the nerve-cell. 



More interest has been displayed in recent years in the alkaloids which act 

 on the extreme terminations of various groups of nerves. These are among 



