J^PRIL 28, 1905.] 



SCIENCE. 



671 



so markedly, according to the composition of 

 the medium and conditions of incubation, 

 that they may be disregarded. The turbidity 

 and sediment in broth varies with the age of 

 the culture: what is first turbidity later settles 

 to form sediment and those constant differ- 

 ences which do exist appear to be connected 

 Tvitli the size of the cell aggregates. Organ- 

 isms growing in large groups like most of the 

 Sarcinae produce heavy sediment and often 

 ■colony-like groups on the walls of the tube, 

 while those in which the cells readily separate 

 -exhibit a more diffuse turbidity. The growths 

 on potato and Nahrstoff agar are correlated 

 with the general vigor of a particular race 

 and vary markedly. Temperature relations 

 are similarly inconstant and what marked 

 differences exist are correlated with other char- 

 acters to which we have given weight; for 

 -example, the Streptococci, as a rule, thrive 

 best at the body temperature, while the 

 Sarcinae and many Micrococci grow better or 

 as well at 20°. 



There remain then for the establishment of 

 species the relation of the organism to gelatin, 

 its action upon sugars, its pigment production 

 and its power to form nitrites and indol. In 

 regard to all these points much more thorough 

 study is needed. In particular, almost no 

 ■data exist with regard to indol and nitrite 

 production. By using the first three char- 

 acters with one or two others which are of im- 

 portance in special cases we have made a 

 tentative division of the 445 described forms 

 tinder thirty-one types. A careful comparison 

 of the published descriptions furnished no evi- 

 dence for more true species and 85 cultures, 

 isolated from various sources, and obtained 

 from the principal American laboratories, 

 ■which we have studied in considerable detail, 

 fall naturally under some one of the types 

 •established. S. erysipelatos includes 20 of these 

 cultures, M. aureus 11, M. orhicidaris 8, M. 

 ochraceus 5, M. urece 3, M. cancscens 5, M. 

 candicons and ventriculi 2 each, M. luteus, 

 M. cinnahareus, M. oethehius, 8. suhflava, 8. 

 incarnala and 8. aurantiaca 1 each. It is 

 very probable that our further investigation 

 will warrant the division of some of these 

 types but we present the thirty-one species 



below tentatively and subject to later revision. 

 It must be understood as noted above that in 

 all cases the names mark only types, numerous 

 intermediate races existing between. 



Family COCCACE^. 



Vegetative cells spherical. 

 Subfamily 1. Paracoccace/E (new subfamily). 



Parasites (thriving only, or best, on, or in 

 the animal body) . Thrive well under anaerobic 

 conditions. Many forms fail to grow on arti- 

 ficial media, none produce abundant surface 

 growths. Planes of fission generally parallel, 

 producing pairs, or short or long chains. 

 Genus 1. Diplococcus (Weichselbaum). 



Strict parasites. Not growing or growing 

 very poorly, on artificial media. Cells nor- 

 mally in pairs, surrounded by a capsule. 



Under Diplococcus are three species, D. 

 pneumonice, Weich., D. Weichselhaumii, Trev. 

 and D. gonorrhcem, Neisser — distinguished by 

 the tissue of the host affected, and by the 

 peculiar morphology and staining reactions of 

 the latter species. 



Genus 2. Streptococcus (Billroth). 



Parasites (see above). Cells normally in 

 short or long chains (under unfavorable cul- 

 tural conditions, sometimes in pairs and small 

 groups — never in large groups or packets). 

 On agar streak effused translucent growth 

 often with isolated colonies. In stab culture, 

 little surface growth. Sugars fermented with 

 formation of acid. 



Under Streptococcus we find the vast ma- 

 jority of organisms indistinguishable from S. 

 erysipelatos, Fehleisen. Two varieties may 

 perhaps be recognized, var. involutus Kurth; 

 and var. tenuis (new variety), which fails to 

 coagulate milk. Representatives of another 

 species, 8. enteritidis Escherich, which lique- 

 fies gelatin are occasionally found. 



Subfamily 2. Metacoccace.e (new subfamily). 



Facultative parasites or saprophytes. Thrive 

 best under aerobic conditions. Grow well 

 on artificial media, producing abundant sur- 

 face growths. Planes of fission often at right 

 angles ; cells aggregated in groups, packets or 

 zooglea masses. 



