APPENDIX. 429 



NITROGEN REQUIREMENTS, the necessary nitrogenous food. This 

 is determined by adding to nitrogen-free media the nitrogen compound 

 to be tested. 



OPALESCENT, resembling the color of an opal. 

 OPTIMUM TEMPERATURE, temperature at which growth is most 



rapid. 

 PELLICLE, in fluid bacterial growth either forming a continuous or an 



interrupted sheet over the fluid. 

 PEPTONIZED, said of curds dissolved by trypsin. 

 PERSISTENT, many weeks or months. 

 PLUMOSE, a fleecy or feathery growth. 



PSEUDOZOOGLOEAE, clumps of bacteria, not dissolving readily in 

 water, arising from imperfect separation, or more or less fusion of the 

 components, tut not having the degree of compactness and gela- 

 tinization seen in zoogloeae. 



PULVINATE, in the form of a cushion, decidedly convex. 

 PUNCTIFORM, very minute colonies, at the limit of natural vision. 

 RAISED, growth thick, with abrupt or terraced edges. 

 RHIZOID, growth of an irregular branched or root -like character, as 



in B. mycoides. 

 RING, Same as RIM, growth at the upper margin of a liquid culture, 



adhering more or less closely to the glass. 

 REPAND, wrinkled. 

 RAPID, Developing in 24 to 48 hours. 



SACCATE, liquefaction the shape of an elongated sack, tubular, cylin- 

 drical. 

 SCUM, floating islands of bacteria, an interrupted pellicle or bacterial 



membrane. 



SLOW, requiring 5 or 6 days or more for development. 

 SHORT, applied to time, a few days, a week. 

 SPORANGIA, cells containing endospores. 

 SPREADING, growth extending much beyond the line of inoculation, 



i. e., several millimeters or more. 

 STRATIFORM, liquefying to the walls of the tube at the top and then 



proceeding downwards horizontally. 



THERMAL DEATH-POINT, the degree of heat required to kill young 

 fluid cultures of an organism exposed for 10 minutes (in thin-walled 

 test-tubes of a diameter not exceeding 20 mm.) in the thermal water- 

 bath. The water must be kept agitated so that the temperature 

 shall be uniform during the exposure. 



