SECT. I 



CRYPTOGAMS 



351 



Sub-Class 4. Aseomyeetes 



The Aseomyeetes form a very large class of Fungi, chiefly parasitic, 

 and with a septate mycelium. Probably without any sexual mode of 

 reproduction, they produce spores asexually ^ 



in special sporangia which have the form 

 of asci or tubular spore-cases (Fig. 273), 

 and give rise to a definite number of endo- 

 genous spores (usually eight in a row). 



Many Aseomyeetes are decidedly poly- 

 morphous, and the same Fungus in the 

 course of its development frequently forms 

 both conidia and chlamydospores as acces- 

 sory fructifications. In many cases only 

 the accessory fructifications represented 

 by the conidia or chlamydospores are 

 known, and not the corresponding ascus 

 fruit. Such Fungi are in the meantime 

 classified in systematic works as "Fungi 

 imperfecti." Concerning the physiological 

 cause of the polymorphism of the Aseo- 

 myeetes, and of the successive production 

 of asci, conidia, and chlamydospores, in 

 the different stages of their development, fig- 273.— Portion of the hymenium 

 but little as yet has been determined. £ ™ s^^li 



In the simplest forms of Aseomyeetes, tissue, (x 240.) 

 the Exoasci, the asci are free and spring 



directly from the mycelium ; but in the case of the Oarpoasei, which 

 constitute the great majority of the Aseomyeetes, the asci are produced 

 in special fructifications of varying form which consist of sterile and 

 fertile or ascogenous hyphae. According to the structure of their 

 fructifications, the Carpoasci are divided into three orders. 



1. Perisporiaceae. — The fertile ascogenous hyphse are enclosed by 

 a compact envelope of interwoven, sterile filaments. The ascospores 

 become free only on the disintegration or rupture of this envelope, 

 the perithecium (Fig. 275). 



2. Pyrenomycetes. — The sterile filaments from a flask-shaped peri- 

 thecium, within which is produced the hymenium, a basal layer of 

 erect asci and paraphyses. The spores are discharged at maturity, 

 through an opening at the apex of the perithecium (Fig. 278). 



3. Diseomyeetes. — The sterile filaments form at maturity an open, 

 cup-shaped receptacle or apothecium with the hymenium on its 

 upper, concave surface (Fig. 228) ; or the hymenium is borne on the 

 outer surface of fleshy, somewhat mushroom-shaped fructifications 

 (Fig. 283). 



