176 RELATIONSHIPS OF THE COCCACE^E 



inadequate to distinguish the " staphylococci " of the body 

 from the yellow and white cocci found elsewhere in nature. 

 In the systematic compilations of Migula (1900) and 

 Chester (1901) parasitic and saprophytic forms were in- 

 discriminately mingled. It was necessary, however, to 

 find some basis for grouping the mass of micrococci to 

 which specific names have been given; and both authors 

 resorted to chromogenesis as a primary basis of classifi- 

 cation. The species listed by Migula under the generic 

 name Micrococcus, more than two hundred in number, 

 were arbitrarily divided according to chromogenesis and 

 liquefaction. As a result, the white and orange staphy- 

 lococci were separated from each other, and associated 

 with forms of widely different origin and nature. 



The only attempt at a natural biological arrangement 

 of these organisms, with which we are acquainted, was 

 made by Unna (1900) in a study of the cocci found on 

 the skin in cases of eczema. The primary basis of his 

 classification was the size of the cocci and their behavior 

 during division. Five types of multiplication were recog- 

 nized, according to the number of cell-divisions which 

 took place before the "hull" or connecting membrane 

 between the cells divided also. Certain cultural and 

 biochemical characters were observed; and Moberg and 

 Unna (1900) finally divided one hundred and forty-five 

 cultures, obtained from seventy-four patients, into twenty- 

 three general classes, characterized by the size of the cells 

 and cell masses, the comparative growth at 20 and 37 



