CH. Ill] FUNGI. 69 



probably be isolated pure cultures of the mould. Take 

 spores from these with a sterile needle, and touch the 

 nutrient gelatine of a series of the prepared tubes : this 

 gives pure cultures of fungus for stock. 



(81) Various cultures. 



Prepare a series of small flasks (200 c.c.), plugged 

 with cotton- wool and sterilised. To the flasks (A to E) 

 add 50 c.c. of the following liquids : 



A. Pure distilled water. 



B. Solution N minus the dextrose. 



C. Solution N minus the peptone and nitrates. 



D. A 10/ solution of dextrose only. 



E. Solution N. 



[N.B. These experiments need the greatest possible 

 care to avoid any trace of impurity in the salts, water 

 etc.] 



Add to each flask one drop of pure water in which 

 spores have been shaken, and separated by filtering through 

 cotton-wool as described above, taking care that the 

 drop contains only a few spores. If properly done each 

 drop should contain about a dozen spores. Place the 

 flasks in a temperature of 20 to 25 C., and compare the 

 growths, which will be as follows : 



A. No perceptible growth 1 . 



B. Fair growth at first which soon, however, comes 

 to an end. 



1 The miscroscope shows that the spores germinate, but the mycelium 

 does not continue its growth. 



