814 



SCIENCE 



[N. S. Vol. 5XV. No. 647 



generally Gram positive, and liquefy and 

 ferment sugars very actively, while the red 

 chromogens are their opposite in each re- 

 spect. It is thus possible to divide the 

 cocci into groups, each marked by the pre- 

 vailing combination of certain character- 

 istics. These groups are defined in relation 

 to the central type about which they cluster 

 rather than separated by sharp boundary 

 lines; yet they certainly mark natural 

 groups and seem to deserve generic rank. 



The generic groups thus established are 

 six in number. Streptococcus is character- 

 ized by parasitic origins (from the sur- 

 faces of the plant or animal body), feeble 

 growth on media, occurrence of cells in 

 chains or small groups, variable response to 

 Gram stain (though generally a positive 

 one), variable acid production in sugars 

 (often reaching very high values), the ab- 

 Bence of nitrate reduction, and the general 

 absence of gelatin liquefaction. (The 

 species in this genus have recently been 

 very satisfactorily worked out, by the sta- 

 tistical method, by Andrewes and Herder, 

 Lancet, September 15, 1906.) Aurococctis 

 [(n. gen.) is characterized by parasitic 

 origin, good growth on media, orange pig- 

 ment, occurrence of cells in irregular 

 groups, generally positive reaction to Gram 

 stain, and the formation of considerable 

 acid in sugar solutions. Nitrates may or 

 may not be reduced, and gelatin is either 

 not liquefied or liquefied strongly. Albo- 

 coccus (n. gen.) differs from Aurococcus 

 in producing a somewhat heavier growth 

 of white color, in forming somewhat more 

 acid in sugar solution, and in a less vigor- 

 ous action on gelatin. These three genera, 

 with Diplococcus, which stands at the ex- 

 treme end of the series beyond Streptococ- 

 cus, may be grouped in a subfamily, the 

 Paracoccaceffi, which includes parasitic 

 forms producing faint to good growths, 

 made up of chains or groups of cells, gen- 



erally staining by Gram and producing 

 considerable acid. 



The rest of the cocci may be grouped 

 together as Metacoccace^, including sapro- 

 phytic forms, producing vigorous surface 

 growths made up of groups of cells or 

 packets, generally Gram negative and 

 showing a slight action on sugars. Here 

 belong the two generally accepted genera, 

 micrococcus and sarcina, the first showing 

 only irregular groups; the second, packets. 

 In both the organisms are most abundant 

 in air, water and earth, rather than on the 

 body; the surface growths on media are 

 abundant and the pigment is yellow; the 

 Gram stain is usually negative and sugars 

 are fermented very slightly. Gelatin is not 

 liquefied, or liquefied somewhat slowly, and 

 nitrates may or may not be reduced. 

 Finally, Ehodococcus (n. gen.) includes the 

 red chromogens, which show either groups 

 or packets, rarely liquefy gelatin and re- 

 duce nitrates, if at all, only to nitrites and 

 not to ammonia. In other respects they 

 resemble Micrococcus. The group of the 

 cocci, as a whole, shows in each character 

 studied a gradual but continuous series of 

 modifications from the strictly parasitic 

 diplococcus to the strictly saprophytic 

 rhodococcus. 



The methods used in this study have 

 been described in the Journal of Infectious 

 Diseases for June, 1906, and the final con- 

 clusions will shortly be presented in the 

 Journal of Medical Research. 



Actinomyces of the Oral Cavity: D. H. 



Berget, M.D, 



The occurrence of actinomyces organisms 

 in the oral cavity is believed to be a subject 

 of interest, not only from the standpoint 

 of infection starting from this place, but 

 also on account of the possibility that these 

 organisms may be directly injurious to the 

 teeth. 



Four organisms of actinomyces were iso- 



