CHARACTERISTICS OF CULTIVATIONS OF FISSION FUNGI. 167 



be seen that one colony presents a completely smooth, 

 sharp outline, another is bulged out or dentate at its 

 margin, or is provided with small outgrowths, or shows 

 wavy threads, which run out from the colony and back 

 to it again. The surface of the former colonies appears 

 smooth, that of the latter granular ; one is dark, almost 

 black, another brown, a third light yellow ; some can 

 scarcely be distinguished from the surrounding jelly by 

 their colour. 



If by this means of distinguishing and recognising 

 the species of bacteria it nevertheless turns out that 

 certain species do not differ in their growth on plates, 

 the growth along strokes, or along a puncture, may 

 show something characteristic. This is ascertained by Char .icteric- 

 pouring the nutrient jelly into test tubes, and allowing puncture 

 it to solidify in some of the tubes in an upright position, 

 and in others in an oblique or almost horizontal layer. 

 Then a small quantity of the colony which has grown 

 on the plate is picked up on the point of a pieco 



Fig. 40. Puncture cultivations in gelatine. 



of platinum wire, and long scratches are made on the 

 surface of the oblique gelatine, while in the other tubes 

 punctures are made with the wire to the depth of about 

 4 cm. Along the punctures we either find only small 



