NATURE OF THE ACTIVE PRINCIPLES 317 



Branhaiii and Lillie (i9.'?2) made comparative studies on the 

 effect of intiacisternal injections of live virulent strains of recently 

 isolated meningococcus cultines killed by fjoiling for five min- 

 utes, and meningococcus "agar washings" filtrates potent in the 

 elicitation of the phenomenon of local skin reactivity. The injec- 

 tions ^vere made directly into the cisterna magna imder light 

 ether anesthesia. Tiiey concluded that all the three inocula pro- 

 duced essentiallv identical histological pictures. \^iriations in 

 intensity ^vere correlated ^vith the time interval from inoculation 

 to death, ratiier than ^vith the inocidum used. The tendency to 

 invasion of the brain substance was possibly less with the filtered 

 suspensions than Avith the li\e or boiled cidtiues. The most sig- 

 nificant iiistological finding Avas pmident or fibrinopiuulent 

 leptomeningitis. It Avas generally most marked o\er the base of 

 the pons and se\eral peduncles aroiuid the midbrain and thalamus 

 and in the cerebellopontine angles. There Avere miliary intra- 

 cerebral abscesses. In the more extensive forms of meningitis 

 pmulent and sanguino-pinulent exudates were sometimes foinid 

 in the Aentricles. Occasionally, edema and lymphocytic infiltra- 

 tion of the choroid plexus, and meningeal and intracerebral 

 hemorrhages Avere seen. The most extensive changes Avere foinid 

 in three animals killed twenty-fi)ur to forty-eight hoins after in- 

 jection. (Tavo Avere inoculated Avith living cocci and one with 

 filtrate.) Tavo animals dying eight hoius after an injection of 

 filtrate shoAved toxic degenerati\'e changes in the nerve cells and 

 no evident meningeal reaction. The brain of rabbits which re- 

 ceived the filtrate presented the histological picture indistinguish- 

 able from those dead folloAving the injection of living or killed 

 meningococci. The histopathological picture was one of acute or 

 subacute meningitis Avith a meningeal exudate composed chiefly 

 of polymorphonuclear leucocytes with a \ariable amoiuit of fibrin 

 and lymphocytes. These authors conclude that experimental men- 

 ingitis in rabbits may not necessarily be an infection, and that 

 intoxication may play a role. 



It appears, then, from Avhat has been just said that lethal 

 factors in certain bacterial filtrates may run parallel to some 

 extent with the acti\ e j^rinciples of the phenomenon. .\s the ques- 

 tion stands now, it would be unwarranted to insist upon the iden- 

 tity of the lethal factors and active princii:)les of the phenomenon. 

 They may simply coexist l)ecause their production is brought 

 about by identical conditions. Further investigations are necessary. 



