NATURE OF CYTOST 235 



A solution of the ash obtained from cats' muscles 

 was prepared, containing 0.112 gm. of the ash per 

 1 cc. of solution. This was injected intraperitoneally 

 into guinea pigs in order to determine the minimal 

 lethal dose of the solution. Proceeding in this fashion, 

 it was found that the minimal lethal dose of the solu- 

 tion when injected intraperitoneally was from ^ to 

 Yi cc. per 100 gms. The lesser quantity caused the 

 death of 50% of the injected guinea pigs within 48 

 hours, and 1^% within 72 hours, whereas the higher 

 quantity always caused death within 15 minutes. In 

 consequence, it must be concluded that qualitatively 

 the guinea pig and cat tissue ash both contain some- 

 thing toxic to guinea pigs. When, however, one com- 

 pares the minimal lethal doses of the two solutions, it 

 is noticed that on a weight for weight basis the solu- 

 tion of guinea pig tissue ash is more toxic for guinea 

 pigs than is the solution of cat tissue ash. 



This is made evident by comparing the quantities 

 of the two solutions which are necessary to cause the 

 death of guinea pigs within fifteen minutes. In this 

 respect, Yi cc. of the cat tissue ash solution contain- 

 ing 0.056 gm. of ash is equivalent to ^ cc. of the solu- 

 tion of guinea pig ash containing 0.028 gm. of ash. 

 Considering the weights of the ash involved, it is ap- 

 parent that the homologous ash is twice as potent as 

 is the heterologous. 



The same result was obtained when the ash of beef, 

 dog, and rat tissue was substituted for the cat tissue 

 ash used in the above experiments. In each instance 

 it was found that solutions of those ashes were all capa- 

 ble of causing the death of guinea pigs when injected 

 intraperitoneally, but that the amounts necessary to 



