CH. Ill] FUNGI. 61 



Potassium nitrate 0'5 



Magnesium sulphate crystals 0'25 

 Potassium monophosphate 0'25 



Calcium chloride 0"01 



Pure water 1000 



Take 1000 c.c. of solution N and add to it 100 grams 

 of pure gelatine (Coignet's gold label) ; sterilise in a flask 

 plugged with cotton-wool, filter while hot and distribute 

 into sterile plugged tubes : sterilise and preserve for use. 



Expose a saucer of solution N to the air, until it is 

 infected with one of the blue moulds: — Penicillium or 

 Aspergillus. With a sterilised needle remove spores of 

 the mould selected and shake up in a small flask of pure 

 water : rapidly filter through a sterile funnel, plugged with 

 cotton-wool to make the spores separate from one another. 

 Add one drop, or more, according to the quantity of spores 

 in the water, to a tube of the gelatine just liquefied, and 

 pour it into a sterile glass dish. When set, put it aside 

 at 20° C. in the dark; after 48 hours or so there will 

 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. 



