66 



Scientific Proceedings (47). 



7. The appearance of any of the protozoan forms under con- 

 sideration, excepting Amoeba, in appreciable numbers at the bot- 

 tom is most often coincident with, or immediately subsequent to, 

 its surface maximum, and portends its more or less rapid elimina- 

 tion as an important factor in the life of the infusion. 



8. Numerous abnormal individuals and cysts are frequently 

 to be found at the bottom in great abundance immediately after 

 the surface maximum. 



9. Emphasis is put upon the strictly biological interrelations 

 (e. g., those involving food and specific excretion products) of 

 the various forms as the most important determining factors in 

 the observed sequence. 



48 (657) 



The experimental demonstration of the identity of so-called 

 Brill's disease to typhus fever. 



By J. F. ANDERSON and J. GOLDBERGER. 



[From the Hygienic Laboratory.] 



The rhesus monkey is susceptible to infection by inoculation 

 with the blood from a case of " Brill's disease." One attack of 

 the disease in the monkey induces a definite immunity to a sub- 

 sequent infection with virulent blood of the same strain. Monkeys 

 recovered from an infection with " Brill's disease " have been 

 found to be immune to a subsequent infection with virulent blood 

 from a case of Mexican typhus fever. Monkeys recovered from 

 an infection with Mexican typhus fever have been found to be 

 immune to a subsequent infection with " Brill's disease." 



From the above results we conclude that the disease described 

 by Brill is identical with the typhus fever of Mexico, and inasmuch 

 as the New York strain is undoubtedly of European origin, we may 

 also conclude that the typhus of Europe and the tabardillo of 

 Mexico are identical. If this conclusion is correct, typhus fever 

 has been present in New York City for a number of years and, 

 according to verbal reports made to us, has occurred in other large 

 cities of the United States. These results make the clinical recog- 

 nition and study of typhus fever of increased importance and 

 necessitate the exercise of appropriate prophylactic measures. 



