708 



INFECTION AND IMMUNITY. 



The first dose in the Hogyes method according to 

 this scale represents 150 units. Naturally those 

 methods in which dried virus is used for at least 

 part of the treatment can not be expressed in units 

 until the infective value of the cords dried for dif- 

 ferent periods is determined. This was investi- 



gated by Harvey and McKendrick and their con- 

 clusions were as follows: "(1) Emulsion of the 

 nine-day cord is little if at all infective in a dose 

 of 0.2 c.c. of a 1 in 5 emulsion. (2) Emulsion 

 of five-day cord is infective in minimal time in a 

 dose of 0.2 c.c. of a 1 in 100 emulsion, but be- 

 come less so or not at all in a dose of 0.2 c.c. of 



