CHICK EMBRYO MEDIUM - RECIPE 35R5-410


"The chick-mash medium consists of finely ground twenty-day


incubated eggs, containing alfost fully matured live chicks and


water.  The eggs are passed through a meat-chopper, eggshell and


all.  To this mash is added from three to seven parts of water. 


The mixture is placed in the refrigerator for 24 to 48 hours, then


transferred to tall tubes or flasks, autoclaved at 17 pounds'


pressure for 20 minutes, and then layered with sterile liquid


petrolatum."






LIMITATION OF EARLIER WORK ON POLIO DISCUSSED   35R5


  In 1935 Dr. Rosenow [35R5] reported that while symptoms of


poliomyelitis had regularly been reproduced by injections of


streptococci freshly isolated from polio victims, that "the lesions


induced, however, were usually atypical, both in type and


distribution."






LIMITATION OF EARLIER WORK ON POLIO OVERCOME WITH CHICK MASH 35R5


TRANSFORMATIONS: STREPTOCOCCUS TO VIRUS TO STREPTOCOCCUS  35R5


SERIAL DIULTION CULTURE, FIRST TIME USED TO ISOLATE ORGANISM 35R5


  "Each of four [streptococcus] strains has been passed


consecutively through the 'streptococcal to virus' phase and


through the 'virus to streptococcal' phase three times."  The use


of "a new medium, autoclaved chick mash", allowed for development


of characteristic symptoms and lesions of "natural" virus, and


apparent transformation of streptococcal into viral forms.  The


reverse action involved high dilution: "The dilution of the virus


from which these streptococci were isolated was extremely high


(200-10 to -21)."


  This was Dr. Rosenow's first use of serial dilution cultures,


which he extended to use with inoculuum of virus and phage into


dextrose-brain mediums [38R5], which method was to become the


general practice in subsequent works involving the isolation of


streptococci.