MICEOCOCCI PATHOGENIC IN MAN. 183 



which is said to occur in coccus forms; this form was 

 observed " when the cultivations were rendered impure by the 

 presence of other small bacteria, the species under discussion 

 retaining, however, the upper hand; the torula-like chain 

 form can then by purer cultivation be again transformed 

 into that of the smooth rods." Undoubtedly such a trans- 

 formation in very impure cultivations is not free from objec- 

 tion. Thus a number of apparent proofs of the mutability of Constancy of 

 form of the fission fungi have been refuted or recognised as un- ! P et ma'^orit 

 certain, while on the other hand we convince ourselves daily of the 

 how extraordinarily constant the most various saprophytie bacteria, 

 and pathogenic species of bacteria are when full attention is 

 paid to all the sources of error. On the ground of these ex- 

 tensive and daily observations one may now with justice assert 

 that variation in form does not occur to any large extent in 

 the majority of the bacteria; that on the contrary most 

 bacteria pass through only the limited cycle of forms which 

 are easily observed and permit a diagnosis of the individual 

 varieties. Should, however, new and unobjectionable investi- 

 gations demonstrate an extensive mutability of form in one 

 or other species, these species must then be classed with the 

 fungi included in the last division of this provisional classi- 

 fication ; we would, however, be compelled to regard such a Express 

 state of matters rather as the exception than the rule, and the^s^ibnit 

 would not be warranted in deducing a law applicable to all of exception* 

 other bacteria from such exceptional cases, seeing that mani- 

 fold investigations have always proved the contrary. 



I. MICKOCOCCI. 



(For characteristics, see p. 171.) 



A. MICEOCOCCI PATHOGENIC IN MAN. 



Staphylococcus pyogenes aureus. 



First observed by Ogston ; cultivated by Rosenbach, 

 later by Krause and Passet. Small isodiametric cells 

 about 0*87 ^ in diameter (Passet). Often grouped as 

 diplococci, at times in 4's, and also in short chains of 3 

 or 4 individuals, generally, however, in larger irregular 

 masses. Ketains the aniline stain after treatment with 

 Gram's fluid (iodine and iodide of potassium solution 

 and alcohol). Grows on gelatine plates,* and forms in 



* Where we speak of nutrient jelly in the following pages we always 



