YEASTS AND MOULDS 337 



most commonly occurring of all moulds. In this genus, 

 the mycelial threads are septate or many-celled. Hyphse 

 are given off, and from the end of each hypha, two or 

 more short pencil-like branches arise, and these likewise 

 give origin to other similar branches. These last, or 

 further set of branches, produce spores or conidia, which, 

 remaining attached, form a string of spores. The branches 

 producing the spores are called sterigmata, and the inter- 

 mediate branches the basidia or conidiophores. The 

 result is not unlike an #-ray photograph of the arm, in 

 which the humerus represents the hypha, the radius and 

 ulna two basidia (omit the wrist), the metacarpus five 

 sterigmata (say three from the radius and two from the 

 ulna), each sterigma bearing spores the phalanges. The 

 spores are rounded in shape. Penicillium glaucum grows 

 on bread paste, showing at first a white fluffy growth, 

 becoming either green or blue, as the spores form. It 

 sometimes is covered with little drops of dew-like fluid. 



On gelatin plates it grows as small round colonies of 

 hair-like filaments, at first white in colour, but later 

 greenish. The gelatin is liquefied. In gelatin stab a 

 white fluffy layer or scum rapidly forms on the top, and 

 descending branches run into the gelatin, as well as hori- 

 zontal ones from the stab. The medium becomes bluish 

 or greenish, and liquefaction takes place. Growths on 

 agar and potato have similar characters. 



Penicillia have been described as the cause of chronic 

 catarrh of the Eustachian tube, and of gastric hyper- 

 acidity. 



Microsporon furfur Is a mould first described in 1846, 

 and found in the skin affection called pityriasis versicolor. 

 It is composed of sinuous hyphae, 3 micra in thickness, 

 showing right-angle branches. The spores are large, 

 3 to 5 micra in diameter, and are formed in a manner 

 similar to that in penicillium. 



Pityriasis versicolor is seen in persons subject to profuse 

 perspiration, who have been infected with the spores from 

 the air or elsewhere. The fungus grows in the superficial 

 layers of the epidermis, forming a yellowish' or coffee- 

 and-milk coloured patch, usually seen on the chest or 

 abdomen or back. Little or no discomfort is caused to 



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