NATURE OF CYTOST 233 



peratures — in the neighborhood of 300° C, for at 

 higher temperatures the ash loses its toxicity. It be- 

 comes practically inactive if fired at 700° C. in an 

 electric furnace. In the experiments discussed below, 

 the various tissues were always ashed at a temperature 

 approximating 300° C. 



In order that we might compare the toxicity of 

 various cytost preparations, we have adopted as a 

 convenient reference standard a solution containing 

 0. 11 2 gm. of ash in 1 cc. This was prepared by extract- 

 ing a weighed quantity of a given ash with sufficient 

 water to yield a solution of this concentration, boiling 

 for a few minutes, and then removing the slight quan- 

 tity of insoluble material by filtration. 



Various quantities of a solution of the ash of guinea 

 pig muscle prepared in this way were injected sub- 

 cutaneously into a large number of guinea pigs. As 

 much as 1.5 cc. of the solution per 100 grams was in- 

 jected in this manner without the occurrence of a 

 single death. 



Animals which received such large injections were 

 ill for a day or two following the injection, but made 

 uneventful recoveries within a few days, although the 

 skin sloughed off at the site of injection. 



Much more striking results were obtained by In- 

 jecting the solution of the ash intraperitoneally. 

 When injected in this manner, %6 cc. of the solution 

 proved lethal to all of 10 guinea pigs which received 

 this quantity. A few minutes after the injection the 

 coats of these animals appeared ruffled, and their res- 

 piration rate increased. Many of them vomited, and 

 all died within from IS minutes to 2 hours following 

 the injection of the cytost. Slightly larger doses — i.e., 



