THE GENUS MICROCOCCUS 215 



series of cultures, and a study of the published descriptions 

 in the literature of the group, are sufficient for the recog- 

 nition of a few of the most obvious types. 



The commonest Micrococcus, according to our inves- 

 tigations, is a form which liquefies gelatin but fails to 

 reduce nitrates. Of our one hundred and fourteen strains, 

 fifty-eight were of this type. In habitat, Gram reaction, 

 surface growth, and fermentative power, these cultures 

 conformed closely to the general characters of the genus 

 as previously described. The liquefaction of gelatin 

 was much slower than in Aurococcus aureus but corre- 

 sponded fairly well with that exhibited by the albococci. 

 Of the fifty-eight cultures, twenty-seven showed a lique- 

 fied layer between .6 and 1.0 centimeter deep, and twenty 

 showed a layer between 1.1 and 1.5 centimeters deep, 

 after two weeks. 



The earliest clear description of a liquefying yellow 

 saprophyte appears to be that of Fliigge in the 1886 edition 

 of Die Mikroorganismen. To this, he attaches the name 

 M . flavus liquefaciens, which Migula modifies to M. 

 flavus (Fliigge). This name may well stand' for the first 

 type center of the micrococci. With the additional char- 

 acters indicated by our own investigation the type may be 

 defined as follows: 



1. M. flavus (Fliigge) Migula. A saprophytic or semi- 

 parasitic coccus, found most commonly in earth, water, and 

 air, frequently also on the surfaces of the animal body. 

 Occurs singly, or in pairs, or irregular groups. Generally 



