EU-MYCETES.— (a) ASCOMYCETES 



433 



commonest are readily distinguished by their stature and colour. 

 Low-growing, velvety, blue-green patches are Penicillium crustaceum ; 

 coarser, ohve-green patches, with mop-like heads, of size visible 

 to the naked eye, are Aspergillus [Eurotium) herbarioruvi. As the 

 patches of the latter grow older, minute yellow specks may appear 

 upon them : these are the Eurotiutn-huits, a stage originally described 

 as a distinct fungus. A breath will carry away the numerous conidia 

 from such a culture in a dense cloud. They form part of the ordinary 

 dust of dwellings, and this accounts for the constant appearance of 



Fig. 36G. 



Conidiophores of Aspergillus herhariorum (to the left) and of Penicillium crustaceum 

 {to the right.) (From Strasburger.) Higlily magnified. 



the Moulds on organic substrata where the conditions are favourable 

 to their growth, as in the moist air in a close cupboard, or under a 

 bell-jar. 



If a sample of Aspergillus be taken, the branched and septate 

 mycelium is seen to ramify over and penetrate into the organic 

 substratum, deriving nourishment till able to propagate. Stout 

 branches then rise upright as conidiophores, which swell upwards 

 into a spherical head. On this numerous conical sterigmata bud 

 forth, each giving rise to a chain of conidia, formed in basipetal 

 succession. The oldest is distal, and successively others are abstricted 

 off : an arrangement which provides for the due nourishment of each, 

 and the ready removal of those that are mature by any breath of air ; 

 for these minute polynucleate bodies are very lightly attached 

 (Fig. 366). They germinate readily in water or damp air, and the 



