1888.] on Poisons and Poisoning. 227 



records certain personal experiences, chief amongst wLicIi were a 

 tendency to breathe slowly, an enfeebled pulse, and fits of sneezing. 



But now comes the curious part of the story, viz. that at the 'post- 

 mortem on the animals that died under the influence of ozone, the 

 blood was found to be venous. (The results were similar when pure 

 ozonized oxygen was employed.) It is most remarkable that the 

 post-mortem appearances of death from an intensified oxygen should 

 resemble those of death from carbonic acid. 



I give these illustrations to show why there should be reason to 

 doubt whether the physical or chemical properties of an element can 

 ever suggest either toxic activity or physiological action. 

 2nd. Compounds. 



Is there any relationship between the chemical composition or 

 constitution of a compound body and its physiological action ? 



The first series of researches on this question was directed to 

 determining whether, in the case of a salt, the acid or the base was, 

 physiologically, the most important ingredient (Blake 1811). 



No doubt most often the active agent of a salt is the base, but 

 this is by no means uniformly the case. Probably the solubility of 

 a compound and the different proportions of acid to base in the salt 

 (i. e. whether the compound in question be an acid or a basic salt) are 

 agencies which also help to determine the toxicity of the body and 

 its j^hysiological action. 



A second series of experiments was made by Blake for the purpose 

 of showing that, given a series of isomorphic salts, the intensity of 

 physiological action increased with the molecular weight. He further 

 contended that salts crystallising in different forms had different 

 physiological actions. On this basis he constructed a series of nine 

 groups of salts, each group being characterised by special physiological 

 actions, insisting with much reason that we j)ossess in living matter 

 a reagent (so to speak) capable of aiding us in our investigations 

 into the molecular properties of chemical compounds. If from 

 molecular constitution you can determine physiological action, 

 probably from physiological action, conversely, you may determine 

 molecular constitution. 



Another series of experiments in a similar direction were made 

 by Schoff on the Continent, and by Fraser and Crum Brown in this 

 country. 



Of these experiments the most important are those indicating how 

 from bodies of vastly different physiological action you may obtain 

 derivatives having similar j)roperties. 



For example, the physiological action of strychnine is primarily 

 exerted on the spinal cord. As a result, convulsions occur as a 

 prominent symptom. But if we introduce into the strychnine 

 molecule a methyl group (forming methyl-strychnine), the action of 

 the drug is altered — methyl-strychnine paralysing (strychnine stimu- 

 lating) the motor nerves. 



But here comes a curious fact. If we take morphine, or nicotine, 



