874 CHEMOTHERAPY 



regard these symptoms, therefore, as vasoparetic in character. We do 

 not believe that these symptoms are due to the pure molecule of 

 the hydrochlorid of dioxydiamino-arsenobenzol. From various experi- 

 ments which we have carried out we strongly suspect that they are 

 produced by traces of an impurity in the drug. We have devoted much 

 study to discover the particular substance which gives rise to these 

 symptoms, but thus far our efforts have not been attended with success. 

 We shall therefore in our discussion refer to this substance as substance X. 



Different lots or batches of dioxydiamino-arsenobenzol (salvarsan 

 or its congeners) vary in respect to the frequency with which they induce 

 the immediate vasomotor or vasoparetic reactions. Experienced clin- 

 icians, we are sure, will agree that few or no reactions of this character 

 occur after the use of certain lots of the drug, and, on the other hand, 

 other batches seem to be followed by an unusual incidence of such 

 reactions. To be sure, not all patients will exhibit vasoparetic reactions 

 after the use of a poor product, nor will all remain free of these reactions 

 after the employment of a relatively pure product. There are, doubtless, 

 variations in susceptibility to substance X, and some patients will react 

 against the minutest quantity, while others will do so only in the presence 

 of a large amount. It is a common experience for patients to repeatedly 

 exhibit vasoparetic symptoms after salvarsan and yet remain free of such 

 phenomena after the use of neosalvarsan ; the formaldehyd-sulphoxy- 

 late group in this compound is attached to the amino radical, and the 

 process which is employed seems to lessen the formation of substance X. 



The Jarisch-Herxheimer Reaction. This reaction manifests itself 

 in the development of a rash, the extension or aggravation of an existing 

 eruption, or an inflammatory reaction in any syphilitic tissue the result 

 of treatment. It has been observed in the course of mercurial treatment, 

 and before the discovery- of the Spirocheta pallida and the Wassermann 

 reaction it was regarded as of considerable diagnostic importance. Any 

 aggravation of syphilitic symptoms following the administration of sal- 

 varsan or mercury has been interpreted as a Herxheimer reaction. The 

 cutaneous reaction is manifested by edema, redness, pain, and the 

 mucous patches show a similar reaction. Gummas become swollen, may 

 ulcerate, and show increased exudation. The lancinating pains of loco- 

 motor ataxia may be augmented, and various paralyses, due to pressure, 

 may follow in those nerves that traverse bony canals. These effects 

 are also known under the name of neurorelapses. They usually appear 

 two or three months or even four or five months after treatment, and 

 they were at first believed to be due to the contained arsenic and were 

 regarded as constituting a special danger attending the use of salvarsan. 



