STUDIES ON FERMENTATION. OV 



will answer our purpose ; let us boil the liquid, and having pre- 

 viously drawn out the necks, let us close the ends in the flame of 

 a lamp whilst the steam is escaping, as soon as we judge that 

 the air has been nearh^ all expelled. Having prepared ten or 

 twenty of these flasks in this manner, when tliey are cold we 

 may break their points in any place we may be in. The air 

 will rush into the flasks, and we must then seal them up again 

 in the flame of the lamp, and put them aside for future obser- 

 vations. In a certain number of these flasks, as we have 

 already explained in our experiments carried on after this 

 fashion, we shall see some fungoid growths appear, first in the 

 shape of flakes of mycelium floating in the liquid, and after- 

 wards coming to the surface to fructify. Now, it often happens 

 that penicillium glaucum appears alone, so numerous are the 

 spores of this fungus floating in the air. Under such con- 

 ditions, M^e shall evidently obtain a field of sporanges quite free 

 from the presence of other organisms. If we now take ofi" the 

 neck of one of the flasks containing the pure penicillium, 

 and take out some of the germs with our platinum wire, * we 



to tlie life of certain ordinary fungoid growths ; lie has given a formula 

 for the composition of such a medium. It is this that we call here 

 *' Raulin's fluid " for abbreviation. 



Water 1,500 ] Carbonate of Magnesia . . 0-4 



Sugar Candy 70 Sulphate of Ammonia. . . . 0'25 



Tartaric Acid 4 Sulphate of Zinc 0*07 



Nitrate of Ammonia 4 Sulphate of Iron 0'07 



Phosphate of Ammonia . . 0*6 Silicate of Potassium .... 0-07 

 Carbonate of Potassium . . 0'6 | 



J. Eaulin. Paris, Victor Masson, 1870. These pour le dodorat. 



* If we do not wish to take the chance of pi'ocuring the pure penicillium 

 by means of these spontaneous sowings, effected by opening and then 

 closing in the flame a certain number of flasks with drawn-out points, 

 we may utilize one of the flasks, which, having been opened and closed 

 again, has notwithstanding developed no organized forms, as follows : — 

 We impi'egnate the contained liquid directly, by dropping into it from a 

 metallic wire spores taken from any growth of penicillium exposed to the 

 common air ; and then from the new field of sporanges formed by this 

 sowing in the flask that has been re-closed, we must, later on, take the 

 pure spores that we require. This method is quicker and almost as safe. 



