670 



SCIENCE. 



[N. S. Vol. XXI. No. 539. 



phology, then according to liquefaction, etc. 

 Larger groups at least should manifestly be 

 indicated by the collocation of several char- 

 acters, the association of any two of which 

 markedly strengthens their significance. By 

 applying this principle, five fairly well-marked 

 genera of coccacese may be distinguished. 

 Four of these, Sarcina, Micrococcus, Strepto- 

 coccus and Ascococcus date back to the early 

 days of bacteriology, although the latter term 

 has fallen into disuse. The mere property of 

 zooglea formation should not be considered of 

 generic importance, but the few peculiar 

 species which are capable of growing under 

 purely saprophytic conditions and producing 

 large gelatinous masses, are so far marked off 

 from other cocci as to warrant, in our judg- 

 ment, the retention of Cohn's genus. The 

 genera Micrococcus, Streptococcus and Sarcina 

 Are retained, since in them morphological dif- 

 ferences appear to be correlated with differ- 

 ences in biochemical characters or habitat and 

 we have considerably enlarged the definitions 

 of these genera to include physiological and 

 ecological factors. With regard to the genus 

 Diplococcus suggested by Weichselbaum for 

 the parasite of pneumonia it should be remem- 

 bered that any coccus may at times occur in 

 pairs. Yet those organisms which are strictly 

 parasitic and which normally occur only in ag- 

 gregations of two cells appear to mark a valid 

 group. The morphological character of a 

 genus must never be too rigidly interpreted. 

 It refers to the typical and most commonly 

 characteristic growth forms; and other 

 groupings may at times occur. Therefore, 

 we recognize five genera, based in each case 

 on a more or less constant association of sev- 

 eral independent characteristics. The old 

 genera Merispomedia and Staphylococcus are 

 merely synonyms of Cohn's Micrococcus, and 

 Ascococcus antedates Leuconostoc. Fischer's 

 characterization of Pediococcm by regular 

 division into two sections at right angles to 

 each other, rests upon a variable and thor- 

 oughly artificial character and probably in- 

 cludes some species of Micrococctis and some 

 imperfectly studied species of Sarcina. 



With regard to the genera, Planosarcina and 

 Planococcus, founded upon the single char- 



acteristic of the possession of flagella there 

 may be more uncertainty. The slow revolu- 

 tion and steady translation observed by Ali- 

 Cohen and Migula as associated with flagella, 

 is certainly a phenomenon distinct from 

 the irregular vibratory and rotary movements 

 noted by other observers, but the resemblance 

 between motile and non-motile forms is so 

 close in all other characters that we can not 

 consider this single property to be of generic 

 importance. 



The five genera above mentioned have been 

 discussed first because their characteristics are 

 already somewhat familiar; but in logical 

 order the larger subdivisions should have been 

 previously considered. 



The family Coccacese, although defined only 

 by the spherical form of the individual, is a 

 thoroughly satisfactory natural group, its 

 members being also marked off in certain 

 physiological characters from individuals of 

 other groups. The family appears to be 

 divisible into two subfamilies. The first, for 

 which we suggest the name Paracoccacess 

 (paratrophic cocci), includes Diplococcus and 

 Streptococcus, parasitic forms which do not 

 develop abundant growth on artificial media 

 and which thrive better under anaerobic 

 than under aerobic conditions, and appear in 

 small cell aggregates of pairs or chains. The 

 second subfamily, the Metacoccaceae (meta- 

 trophic cocci), includes Micrococcus, Sarcina 

 and Ascococcus, saprophytic or semi-sap ro- 

 phytic types which are aerobic and form 

 abundant surface growths of large cell groups. 



The species of the coccacese are consider- 

 ably more obscure. We have reviewed the 

 descriptions of 445 supposedly distinct species 

 given by Cohn, Migula, Fliigge, Chester, 

 Sternberg, Lehmann and Neumann, Engler 

 and Prantl, Rabenhorst, Frankland and 

 Woodhead and find a wonderful amount of 

 duplication. Our observations have con- 

 vinced us that minute differences in mor- 

 phology, as for example, the distinction be- 

 tween large and small cells or long and short 

 chains, are not sufficiently constant for the 

 erection of species. Again, slight differences 

 in the appearance of colonies on gelatin, which 

 form a large number of German species, vary 



