not measured by its poisonous cell content, but by the rate 

 with which it multiplies in the animal body or the intensity 

 and rapidity with which it converts body proteins into its 

 own proteins. 



It must be borne in mind in considering what we are 

 about to say in this paragraph that at the time these experi- 

 ments were conducted we knew but little about protein 

 sensitization, and they were not conducted with the phe- 

 nomena of sensitization in view. Had we known then what 

 we now know the lines of investigation would have been 

 drawn somewhat differently. However, this makes a review 

 of our old protocols all the more interesting and valuable. 

 We tried to immunize animals with the cellular substance. 

 It will be worth while to follow one set of these experiments 

 through. We take the three tables on p. 210 just as they 

 stand in the protocol. 



It will be observed that in the second and third injections 

 made at intervals of five and six days we killed one-third 

 of our animals. Now we know that this was due to the 

 fact that we partially sensitized the animals. 



Failing absolutely to even render our animals tolerant 

 to the dead germ substance, we tried to weaken it by heat, 

 but in this we were equally unsuccessful. However, we 

 did prove that heating the cellular substance of the pneu- 

 mococcus to 144 for five minutes in the autoclave does 

 not destroy its intracellular poison. We also found that 

 by heating the cells some of the poison passes into solution, 

 and may be filtered through porcelain. 



We split up the cellular substance with a 2 per cent, 

 solution of sodium hydroxide in absolute alcohol, and 

 obtained a non-poisonous and a poisonous portion. In 

 both small and large doses the former had no visible effect 

 on animals, but it gave no immunity to subsequent inocu- 

 lations. 



The poisonous fraction kills animals in about the same 



doses as are required by similar preparations from other 



proteins. The symptoms are not wholly identical with 



those induced by poisons obtained from other proteins. 



14 



