LESSON ii SEPARATION OF PROTEINES 145 



(8) Filter through paper, and wash the residue on the 

 filter with the dilute hydrochloric acid, and then with dis- 

 tilled water. 



(9) Dissolve the washed residue in the smallest possible 

 quantity of a sterile '5 per cent solution of caustic soda. 



Eesult : alkaline solution of mycoproteine. 

 Tests : (1) On neutralising, no precipitate. 



(2) Make the solution slightly acid, and add a 

 little salt : a precipitate appears. 



(b) Bacillus prodigiosus. 



(1) Inoculate twenty potato tubes with the Bacillus pro- 

 digiosus, spreading the material thoroughly over the surface 

 of the potatoes ; and keep them at 22 C. 



(2) When there is a copious growth, treat the cultures 

 with -5 per cent solution of caustic potash, as described 

 above. 



(3) Collect the caustic potash emulsions, and proceed 

 exactly as before. 



(c) Precipitation by alcohol. 



(1) Inoculate twenty potato tubes with the Bacillus pro- 

 digiosus, and keep them at 22 C. 



(2) When there is a copious growth, with a blunt scalpel 

 scrape the cultures off the surface of the potatoes. 



(3) Spread the scrapings, in a thin layer, over a plate of 

 glass, and exsiccate rapidly by means of dry heat (up to 

 100 C.) 



(4) Scrape the dried culture mass off the glass plate, 



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