290 MICROBES AND TOXINS 



the Chinese had employed it. As soon as it was found that 

 sleeping sickness had as its cause a trypanosome, the arsenical 

 treatment was applied to it. But arsenious acid was too toxic 

 to be easily employed, and the discovery of trypan-red and the 

 first successes reported with the chroniotherapy might have led 

 to its abandonment, had not W. Thomas brought again into 

 prominence the substance atoxyl\\\ 1905. Atoxyl, discovered 

 by Bdchamp in 1863, hardly entered the sphere of human 

 medicine until 1902, when it was employed in dermatology, 

 both by intravenous and subcutaneous inoculation. Thomas 

 has the credit of employing it against sleeping sickness. 



It' is not, as was first thought, metarsenical aniline, which 

 contains 377 per cent, of arsenic. According to Ehrlich and 

 Bertheim, it is the monosodic salt of paraminophenylarsenic 

 acid, but it is still the compound discovered by B&hamp. 



It contains 24 per cent, of arsenic. It is a white, crystalline 

 powder soluble in water and easily sterilised. It may also be 

 applied as an ointment. Although almost thirty times less 

 toxic than arsenious acid excessive doses produce nephritic 

 symptoms and above all disturbance of vision reaching even to 

 complete blindness. 



Atoxyl has been employed in the trypanosome infections 

 and in several spirillum diseases, such as recurrent fever and 

 syphilis : it exerts both a prophylactic and a curative action. 

 It has been said that it no longer acts in the trypanosomes in 

 sleeping sickness once these have penetrated into the cerebro- 

 spinal fluid : but according to several observers the meninges 

 are in general quite permeable (L. Martin). In vitro it acts 

 neither on trypanosomes nor on spirilla, so that the body itself 

 must play an active part in the treatment. 



Atoxyl would be a perfect remedy were it non-toxic. By 

 ringing the changes on the chemistry of this arsenical subject 

 a series of compounds have been discovered of which the last 

 is 1,500 times less toxic than the first. 



Three compounds superior to atoxyl have been discovered 

 in this series : in the first place arsacetm, which is four times 

 less toxic than atoxyl for the mouse and distinctly less toxic 



