Recently described in vitro tests of bacteria1 have been shown to give results parallel with certain pathogenic properties of the cultures and with other biologic findings.10 Although cultures reacting positively to these tests are probably pathogenic,10 for clarity they will be referred to as "in vitro positive" rather than "probable pathogenic." The development of these tests has made possible the study of the relation of large numbers of staphylococci and streptococci associated with chronic, and sometimes with acute, illnesses. In the investigation to be discussed the methods were used in the study of the distribution of probable pathogenic staphylococci and streptococci in patients with low grade chronic illness. Observations on the distribution of the sedimentation rates and nonfilament-filament ratios of 292 of these patients have been reported.2
MATERIAL
Of the 395 patients studied, most of them showed more than one disease, 96.3 per cent had clinical evidence of involvement of