THE SPECIES OF THE GENUS PENICILLIUM. 339 



ticularly described by WEIIMER (XX.), are usually abundant, 

 occurring on the surface of the vegetation as lemon to golden 

 yellow, thin-skinned bodies, more or less spherical, 1-2 mm. in 

 diameter, turning dark orange with age, and ultimately becoming 

 discoloured. The integument, which is about 100 yu thick, 

 formed of loosely woven hypha? and of a golden yellow (afterwards 

 brownish red) colour, encloses a colourless network of filaments 

 with embedded nests of ellipsoidal asci (measuring 9-11 by 6-8 /z), 

 each of which contains 4-8 (average 5) barrel-shaped, tough- 

 walled spores (4-5 by 2-8 p). In contrast with those of 

 P. glaucum, Brefeld, these spores have no longitudinal furrow, 

 but are provided with 3-4 delicate transverse fillets, which do 

 not eject the epispore in two halves during germination, but 

 allow the contents to escape through fine cracks and form a 

 voluminous secondary spore, which then develops. In a few 

 weeks the integument of the fruit becomes very brittle, and 

 encloses a pale yellow dusty mass of liberated spores. These 

 ascospores, which at first consist of loosely intertwined bundles of 

 hypha? with separated groups of asci, would undoubtedly justify 

 the classification of the species outside the Aspergillacece, the 

 fructification being similar to that of Gymnoascus and differing 

 completely from P. ylaucum, Brefeld. The bright yellow colour 

 of the young mycelium arid fruit case of P. luteum is due to 

 yellow granules (a pigment soluble in alcohol and classed by 

 Zukal as a fungus acid), abundantly secreted by the hypbre and 

 forming a dense coating upon them. These are lacking in 

 P. glaucum, and are not invariably met with in P. luteum. The 

 fungus readily acidifies saccharine nutrient media by the forma- 

 tion of free citric acid. 



Penicillium italicum, Wehmer, is a mould which, according to 

 WEHMER (XXIX.) is found only on certain substrata (pine- 

 apples, lemons, oranges, and similar southern fruits), and differs 

 from those already described by the bluish grey shade of the 

 green surface. The structure of the conidiophores (see Fig. 180) 

 corresponds with that of P. glaucum, Brefeld, but the conidia are 

 ellipsoidal instead of spherical. This fungus, which is very 

 commonly imported with the fruits in question, is the cause of ex- 

 tensive putrefaction, for instance, in the case of ripe pine-apples, 

 the entire contents of the closed cases being sometimes destroyed 

 in this way during transport. The rapid spread of the mould on 

 the surface is accompanied by an equally rapid penetration of the 

 flesh of the fruit, which is spoiled in consequence. The delicate, 

 colourless conidiophores, which are only of the thickness of hypha3 

 and about 250 /j, long, carry 2-3 upright branches, arranged at 

 unequal heighths and provided with a tuft of (2-6) sterigmata, 

 like the main stem, but not always at the same height. The 

 delicate ellipsoidal conidia, extending in long chains from the 

 slender, tapering sterigmata (measuring about 10 by 3 p), hang 



