262 



METHODS OF IDENTIFICATION AND STUDY 



water which has been expressed during the rapid solidi- 

 fication of the medium and has subsequently condensed. 

 Gelatine and Agar. Examine the colonies at inter- 

 vals of twenty-four hours. 



(a) With the naked eye. 



(b) With a hand lens or watchmaker's glass. 



(c) Under a low power (i inch) of the microscope, 

 or by means of a small dissecting microscope. 



Distinguish superficial from deep colonies and note 

 the characters of the individual colonies. 



(4) Size. The diameter in millimetres, at the various 

 ages. 



(B) Shape. 



Punctiform: Dimensions too slight for defining form 

 by naked eye; minute, raised, hemispherical. 



a b c 



FIG. 141. Types of colonies: a, Cochleate; b, amoeboid; c, mycelioid. 



Round: Of a more or less circular outline. 



Elliptical : Of a more or less oval outline. 



Irregular: Outlines not conforming to any recognised 

 shape. 



Fusiform: Spindle-shaped, tapering at each end. 



Cochleate: Spiral or twisted like a snail shell (Fig. 

 ,141, a). 



