POLIO - ELECTRON MICROSCOPE, NATURAL & ARTIFICIAL VIRUS [42R1-100]


  Comparable forms were found in filtrates of both natural


poliomyelitis virus and artificial polio virus derived vrom


streptococci, and from chick-mash culture of the streptococcus from


poliomyelitis, but not in controls: "Microdiplococci, sometimes in


short chains, of varying size and opacity, were found in each of


the filtrates made of natural poliomyelitis virus, of poliomyelitic


virus derived from streptococci, and of the chick-mash culture of


the streptococcus from poliomyelitis.  Exceedingly small ovoid and


diplococcal forms and short chains of small diplococci, some too


small to photograph, were seen.  The smallest forms seen resembling


organisms approximated the postulated size of the virus particle. 


Some large forms seemingly were breaking into small diplococci


similar to those seen in certain cultures of the streptococcus."


... p. 101: "The films directly from the formalinized cultures in


dextrose-brain broth revealed, in addition to the large organisms,


numerous exceedingly small, elongated oval or diplococcal forms


projecting radially from the margins, with few or no free forms.


... The location, radial orientation, number and uniformity of size


and shape of these 'midget' forms suggest that they are dispersions


of the large organisms and not artifacts. ... this might be a


reason for occurrence of growth ... in [extreme] serial dilution


cultures ..." [see MUTATIONS - L-FORMS]