320 



Messrs. J. Mcintosh and P. Fildes. 



the special action of apple oxidase on tannic acid is due to the presence of a 

 phosphatic sensitiser, it would be a feebler oxidase of the same type. Carrot 

 and parsnip oxidases are a grade feebler, but still react to guaiacum in tbe 

 absence of a peroxide. Malt diastase is still weaker, and papain feebler still, 

 while pepsin may show a weak " peroxidase " reaction with guaiacum, but not 

 any other oxidase action. 



The Fixation of Arsenic by the Brain after Intravenous 

 Injections of Salvarsan. 



By Jambs Mcintosh, Beit Memorial Eesearch Fellow, and Paul Fildes, 

 Assistant Bacteriologist to the London Hospital. 



(Communicated by Prof. W. Bulloch, F.R.S. Received July 8, 1914.) 



(From the Bacteriological Laboratory of the London Hospital.) 



During the period of probation of salvarsan as an anti-syphilitic remedy, 

 a number of toxic phenomena were reported which led to the belief that this 

 drug had particular neurotropic properties, and was therefore to be used 

 with the greatest circumspection. These fears were very largely founded 

 upon the well known effect of the related drug atoxyl in producing optic 

 atrophy. Subsequent experience has, however, shown that the supposed 

 neurotropic action of salvarsan was due to certain technical errors in its 

 administration. 



In 1911 we published (1) an observation which combated the view that 

 salvarsan had neurotropic qualities. We submitted the organs of an infant 

 who died after administration of salvarsan to Dr. W. H. Willcox for 

 analysis, and he reported to us that the brain in this case contained no 

 arsenic, although considerable quantities were present in other organs. We 

 then applied the law of Ehrlich, " corpora non agunt nisi fixata," and argued 

 that, since the brain was free from arsenic, salvarsan could have no neuro- 

 tropic action. 



Exactly similar conclusions were arrived at by Ullmann in 1913 (2). In 

 the course of a very extensive investigation upon the distribution of arsenic 

 in the body after salvarsan injections, he made it quite clear that the brain 

 never contained more than traces of arsenic, and " this fact was evidence 

 against the neurotropic action of salvarsan." Similarly, Morel and 



