78 THE UNIVERSITY SCIENCE BULLETIN. 



ratio groups and whether these correlate with any other characteristics 

 and data. 



In all, 75 strains of staphylococci were studied. These were 

 obtained from pathological conditions, in various foods and 

 three strains from the American Museum of Natural History. 

 My tentative definition for staphylococci was cocci in which 

 the division was in two planes giving rise to flat sheets of 

 cells and irregular masses. 



TECHNIQUE. 



All organisms used in this work were freshly isolated and 

 were first grown upon agar, + 1 to phenolphthalein, then 

 inoculated into plain broth to determine morphology. 



In studying fermentation, the organisms were inoculated 

 into one per cent sugar broth solutions of dextrose, lactose, 

 saccharose, mannite, maltose, salacin, dulcite, inulin, raffinose, 

 glycerin, galactose and xylose, and tested in 48 to 72 hours 

 with litmus. 



For confirmation, the organisms were inoculated into Hess's 

 semisolid medium containing Andrede as an indicator plus 

 the following carbohydrates — dextrose, lactose, saccharose and 

 mannite. 



One per cent peptone lead acetate agar and three per cent 

 peptone lead acetate agar were made according to directions 

 given by Jordan. 



Litmus milk, one per cent peptone gelatin, Dunham's pep- 

 tone, nitrate broth were made according to directions in Stand- 

 ard Methods of Water Analysis. 



Gram stains were made from cultures after 24 hours' growth 

 upon an agar slant, using carbol gentian violet as the primary 

 stain and counterstaining with an aqueous solution Bismarck 

 brown. 



The chromogenic power was determined by spreading a por- 

 tion of a culture two weeks old upon white paper, as suggested 

 by Winslow. 



Blood agar plates were made by adding 3 cc. of whole de- 

 fibrinated blood to 100 cc. of agar neutral to phenolphthalein. 

 Sheep, rabbit and human blood were used. The sheep blood 

 was all obtained from the same animal, three different rabbits 

 were bled, and human blood was obtained from several indi- 

 viduals. 



