YEASTS AND MOULDS. 587 



Aspergillus niger (Enroth (Kf er^ ,, De 



Dark chocolate-brown tufts. Conidia ,,,!. l.|, 1( * ,,, OWJI> o 

 brown when ripe. This mould can be cultivate,! , ..... lih on 

 moistened with vinegar, on slices of lemon, and on ari.l 'lYuus and 

 liquids It flourishes best of all, accorfing to H,mli,,, in 

 or the tollowing composition : _ 



Oraminw. 



LM 



Sugar-candy . - (| . 



Tartaric acid . . . . } . 



Nitrate of ammonia . . i. 



Phosphate ... .,; 



Carbonate of potassium ... .5 



magnesium .... 



Sulphate of ammonia ... 25 



zinc ..... 



iron ...... .07 



Silicate of potassium ... -07 



It was also found that the fungus grew best when tin- 

 was spread out in a layer 2 or 3 cm. in depth in a .-shallow dj 

 and a temperature of 35 C. proved to be the most fa\ 

 The abstraction of zinc from the nutritive liquid reduced the weight 

 of a crop from 25 (the average) to 2 grammes, and the presence 

 f T?OOOOO P art f Citrate of silver, or 50 ooo P art f corr " 

 subHmate, stopped the growth altogether. It is saprophytir in 

 living body. 



METHOD OF EXAMINING ASPERGILLUS NIGER. 



Species of aspergillus stain intensely with rannine. fuchsine or methyl- 

 violet : but to examine Aspergillus niger with a high power ah 

 special technique is employed, as follows : A drop of glycerine is placed 

 on a clean slide, and a drop of alcohol on a cover-glass. With a fine i 

 of forceps a few of the fruit-hyphae with their hlack heads are immersed 

 in the alcohol. The cover-glass is then turned over on to the drop of 

 glycerine, and the slide held in the flame of a Bunsen burner till the 

 spores or conidia are dispersed. To make a permanent preparat 

 remove the cover-glass, and transfer the fruit-hyphie so treated to a 

 mixture of glycerine and water (1 to .".) : a drop may b< 

 placed ready on a slide provided with :i ring of Canada balsam. The 

 specimen is then permanently mounted by .-4 a circular cover- 



glass, and surrounding it with a ring of cement in th- IIMKI! 



