THE MOULD-FUNGI. 91 



sufficiently known, but which in every case appear to be 

 connected with a free supply of nutriment, the mould develops 

 perithecia. These appear at first as tender branches, which, 

 at the termination of their longitudinal growth, begin to 

 twine their free ends in the form of a spiral of four to six 

 turns (/) ; the threads of the spiral gradually approach 

 nearer together, until finally they are brought into contact, 

 so that the entire end of the filament takes the form of a helix 

 (the ascogonium). There then grow from the lowest turn 

 of the helix two or more small branches, which cling closely to 

 the spiral. One of these small branchings ($, T, p) quickly 

 outstrips the others in growth, and its upper extremity reaches 

 the uppermost turn of the helix, and becomes fused with it. 

 The other brancli or branches likewise grow upwards along 

 the spirals, shoot out into new branches, and gradually become 

 so interlaced that finally the spiral becomes surrounded by 

 an unbroken envelope (W). These branches become divided 

 by septa perpendicular to the surface, and the envelope 

 consequently consists of short, angular cells, in which new 

 septa appear parallel to the surface, so that the envelope 

 becomes thicker and composed of many layers (F, X, F). 

 The small sphere now formed is about one-quarter mm. in 

 diameter ; the outermost layer is yellow, whilst the inner 



FIG. 19. 



Eurotium Aspergillns Glaucus de Bary : m, m, hyphal thread, carrying a 

 conidiophore c (from which the conidia have fallen), a perithecium F, 

 and the first rudiments of an ascogoninm, / (X 190) ; .<?, three sterig- 

 mata from the crown of a conidiophore, showing the conidia-constric- 

 tions ; p, germinating conidium (x 250 300); A, ASCIIS; r, 

 germinating ascospore ; k, germ tubes ; S, spiral ascogonium ; at p 

 the commencement of the growth of one of the enveloping hyphse ; 

 T, older stage ; Jf , ascogonium, already surrounded by the envelope ; 

 V, longitudinal section of an older stage ; in the centre the ascogonium, 

 surrounded by the envelope, which now consists of several layers ; 

 X, longitudinal section of a later stage of development ; the ascogonium 

 is enveloped in a sheath of many layers, and it has loosened its convo- 

 lutions, and commences to throw out the ascus-forming branches ; 

 M y portion of an older ascus-bearing branch ; a, a young ascus ; a', an 

 older ascus which has burst. 



