NATURE OF CYTOST 237 



tissues was remarkably toxic to cats. Three cats 

 weighing respectively 2790, 2115, and 2470 grams 

 died within less than a minute after the intravenous 

 injection of 1 cc. of a 10% solution of rat muscle ash, 

 while a fourth cat, weighing 2850 gms., developed a 

 mild shock from which it recovered in 10 minutes, 

 and remained in good health for two weeks, when it 

 was used in another type of experiment. 



The species specificity which is evidenced in these 

 experiments is also brought out by the reaction of cats 

 to intraspinal injections of solutions of homologous 

 and heterologous tissue ash. Ten per cent solutions 

 of the various ashes were injected intraspinally into 

 cats. The solutions of homologous tissue ash when 

 administered in this fashion caused shock, paralysis of 

 the hind limbs, and in some instances death, whereas 

 equal quantities of the ash of heterologous tissues 

 caused only slight transitory symptoms from which 

 the animals promptly recovered. The results of repre- 

 sentative experiments of this type are recorded in 

 Table XIV. (Turck, 1921.) 



These experiments again show the same type of 

 species specificity observed in the other experiments. 

 While 0.25 cc. of the solution of cat ash equivalent to 

 0.025 gm. of ash evokes distinct reaction, four times 

 this amount of the ash from human, horse, and lion 

 tissues causes the recipients but little inconvenience. 

 It is especially interesting to note that of the three 

 heterologous ashes employed in equal quantities, the 

 ash from lion tissue caused the most distinct reaction, 

 although this was far less severe than that caused by 

 an equivalent quantity of cat ash. Phylogenetically 

 the lion is closely related to the cat; hence this find- 



