174 LABORATORY EXERCISES IN BACTERIOLOGY. 



in turn noted, both for the isolated colonies and the diffuse growths, including in each 

 instance the position of growth (whether upon the surface or beneath the surface of 

 the medium), the differences apparent in surface and deep growths, the profuseness or 

 poverty of growth, the color, shape, size, appearance of the margin, consistence, optical 

 characteristics, and internal structure of the focus of growth. The elevation or depression 

 of the surface growths, liquefaction, change of reaction, and other alterations of the nutrient 

 medium, the appearance of gas bubbles in the medium and any peculiar odor are re- 

 corded. In liquid media are noted any changes in transparency and color, the appear- 

 ance of pellicle or sediment; and any changes in the general appearances of the medium 

 (as coagulation of milk) are to be further observed. Modifications resulting from 

 age of culture are likewise to be included in the study. 



From the fact that no definite nomenclature has been adopted in this, as in other 

 branches of physical science, for the description of cultural peculiarities, and in the 

 absence of a definite system of observation, considerable difficulty of recognition has 

 arisen; and it is often almost impossible, from the writings of observers working with 

 the same organism, to be sure of the identity of their material. The personal equation 

 in the description of the form, color, and other characters of a colony, the failure to 

 indicate as the basis of description the exact conditions of growth, and the loose use 

 of descriptive terms are largely the cause of this confusion; and every effort to fix a 

 system of observation and to establish a well-defined nomenclature must be com- 

 mendable. With this purpose in view the following list of descriptive terms, by permis- 

 sion of the author, is included in these pages, adopted from Chester's Manual of Deter- 

 minative Bacteriology. 



(For discussion of color, gas formation, liquefaction of medium, reaction changes, 

 etc., see next chapter.) 



CHARACTERS OF BACTERIAL CULTURES. 



I. Gelatine Stab Cultures: 



(A) Non-liquefying: 

 Line of Puncture: 



Filiform, uniform growth, without special characters (Fig. 51, 1 B). 

 Nodose, consisting of closely aggregated colonies. 



Beaded, consisting of loosely placed or disjointed colonies (Fig. 51, 2 B). 

 Papillate, beset with papillate extensions. 

 Echinate, beset with acicular extensions (Fig. 51, 3 B). 

 Villous, beset with short, undivided, hair-like extensions (Fig. 51, 5 B). 

 Plumose, a delicate feathery growth. 



Arborescent, branched or tree-like, beset with branched, hair-like extensions 

 (Fig. 51, 4 B). 



(B) Liquefying: 



Crateriform, a saucer-shaped liquefaction of the gelatine (Fig. 52, 1). 

 Saccate, shape of an elongated sack, tubular, cylindric (Fig. 52, 3). 

 Infundibuliform, shape of a funnel, conical (Fig. 52, 4). 

 Napiform, shape of a turnip (Fig. 52, 2). 



Fusiform, outline of a parsnip, narrow at either end, broadest below the surface. 

 Stratiform, liquefaction extending to the walls of the tube and downward 

 horizontally (Fig. 52, 5). 



II. Stroke Culture (see plate cultural characters). 



III. Plate Cultures, Colonies: 



