644 



SUMMAKY OF CURRENT RESEARCHES RELATING- TO 



media usecT.were brain, meat-water agar, serum, and bouillon. The 

 acidity was Calculated by means of phenolphthalein. In the case of 

 brain, 100 ccm. was found to have an acidity of l'4ccm. normal acid 

 ( = 56 mg. H 2 S0 4 ). To meat- water agar containing 1 per cent, pepton and 

 * 5 per cent. NaCl was added sufficient soda solution to neutralise two- 



Fig. 177. 



thirds of the acid. Serum was treated with two-thirds to three-fourths 

 of the neutralising soda solution. Bouillon gave the best results when 

 70 per cent, of the total acid was neutralised. The simple expedient of 

 mixing 7 parts neutral and 3 parts acid bouillon was quite unsuccessful. 

 The author is of opinion that a mixture of neutral and bibasic 

 ]ihosphates is necessary for the growth of Gonococcus. 



Cultivation of Dictyostelium mucoroides and other Amoebae.* — 

 Herr G. A. Nadson finds that it is not difficult to cultivate Dictyostelium 

 mucoroides on sterilised manure, and also on gelatin mixed with manure, 

 on malt extract, on alkaline meat-pepton, gelatin, or agar. The colonies 

 look pure to the naked eye, but careful microscopical examination shows 

 that this is not the case. D. mucoroides does not liquefy gelatin ; it is 

 strongly aerobic, prefers slightly alkaline media, but can exist on acid 

 substrata. Fluid media are not advantageous for growth, but pure 

 cultures were obtained in the following nutrient solution : — Aq. dest. 

 100 ccm., glucose 5 grm., pepton Witte 1 grm., potassium phosphate 

 0'1 grm., magnesium sulphate 0*1 grm., traces of calcium and iron 

 phosphates. In most media bacteria were a constant accompaniment, and 

 their presence was favourable to the development of the organisms. 

 The usual companion of D. mucoroides is B. fluorescens liquefaciens, 



* Scripta Botanica, 1899, fasc. xv. Petersburg. See Bot. Centralbl., lxxxii. 

 1900, pp. 227-8. 



