MOULDS OX ARTICLES OF FOOD 193 



cious colonies develop on potato, and give off an odour of 

 putrid fish. 



Bacillus viscosus sacchari. Kramer assigns long rods 

 with rounded corners, which are destitute of motility and 

 frequently arranged in chains, as the cause of solutions of 

 sugar becoming slimy. Gelatine is liquefied, a whitish 

 film develops upon agar, and a firm mass upon potato. No 

 growth takes place on acid media. 



Moulds on articles of food. The moulds find abundant 

 opportunity for development and propagation upon vege- 

 table foods, and the three varieties, PemnUinm, Aspergillmt, 

 and Mucor, are all represented. Pcnicillium yhiucum has 

 already been described under the ' Bacteriological Analysis 

 of Air' (see p. 103). 



The various kinds of Aspergillus flourish on bread and 

 candied fruits. To obtain the Aspergillus niger, bread 

 pap is prepared in an Erlenmeyer's flask. After some 

 time stout fructifying hyphse are found, not ramified at the 

 end like Penicillium, but swollen so as to resemble clubs. 

 Upon these are arranged the sterigmata, at the upper ends 

 of which the spores become segmented off and form aggre- 

 gations which take the form of rounded, bulging black swel- 

 lings. The entire flask soon becomes filled with fibres and 

 grey points. Aspergillus albus and Aspergillus glaucus are 

 similar, but grow better at incubating temperature (see 

 fig. 3). 



The Aspergillus flavescens is distinguished by its well- 

 marked fructifications and the greenish colour of the cul- 

 tures. Aspergillus fumigatus bears very fine fructifications, 

 and forms an ash-grey fur. Both grow luxuriantly on 

 bread at incubation temperature. On gelatine plates fila- 

 ments appear which spread rapidly into the surrounding 

 parts with liquefaction of the medium. 



Of the Mucorineae, the Mucor mucedo, Mucor corymbifer, 



o 



