FUNGI. HYMENOMYCETES. ! o r 



I will add one remark only on the structure of the tissues in this group, namely that 

 in the fructifications of many of the Agaricineae, Lactarius for example, single much- 

 branched hyphae become laticiferous tubes, which give out large quantities of latex if 

 the tissues are injured. 



If we compare the course of development of the Basidiomycetes with that of the 

 group last described 1 , we find that it agrees with that of the species among the 

 Uredineae which like Chrysomyxa Abietis have lost the aecidium, the counterpart 

 of the fructifications of the Ascomycetes, and are propagated only by gonidia, and in 

 the case of Chrysomyxa and others by one form only of gonidia, the teleutospore. 



To this preliminary account of the structure of the fructification of the Hymeno- 

 mycetes we will append as an example the history of the development of Coprinus 

 stercorarius as it is given by Brefeld. The basidiospores germinate at once when sown 

 in a decoction of dung as a nutrient solution, and the germ-tube issues forth at the 

 end of the spore opposite to the sterigma, where there is a small pore. The myce- 

 lium which is now developed is filiform and copiously branched, with frequent coale- 

 scence of cells, such as occurs not unfrequently in other mycelia. Rudiments of 

 fructifications make their appearance in from nine to twelve days on older parts of the 

 mycelium, being formed immediately on single mycelial filaments in small, poorly-fed 

 plants ; in plants of more luxuriant growth sclerotia are usually first formed. These 

 originate in the dense interweaving of branches of the hyphae, which form at first a 

 closely-tangled mass with the interstices filled with air. In a few days the sclerotium, 

 the size of which depends on the supply of food, has arrived at the resting state ; it has 

 a colourless inner tissue, and a black rind the cells of which are united into a firm 

 tissue. Where the i~ind is removed, the part of the inner tissue that is laid bare 

 assumes the character of a rind. In germination the peripheral cells of the rind 

 sprout and form on their surface small flake-like bodies which are rudimentary 

 fructifications. A single one outgrows the rest, which then cease to develope. The 

 formation both of the sclerotia and of the fructifications is therefore purely vegetative, 

 and the sclerotia here are merely resting mycelia, not as in Penicillium a resting state 

 of the fructification. 



The stipe is for a time very short in the young fructification, the pileus being 

 developed before it. Rhizoids are formed in the basal part of the stem, at every point 

 which comes into contact with a suitable object. The development of the pileus 

 terminates with the formation of the rhizoids ; the stalk elongates to more than ten 

 times its former length and the pileus then discharges its spores. 



The formation of sclerotia as here depicted may however be omitted, as happens 

 when the plants are starved, e.g. when grown on a microscopic slide. In this case the 

 fructifications are developed on single filaments of the mycelium as adventitious shoots, 

 which make their appearance on the mycelium produced from a single spore in limited 

 numbers, the maximum being twenty. A hypha branches, and its branches ramify, 

 and the ramifications gather into a coil or cluster. This hyphal coil forms inside it a 

 nucleus of false tissue, the first rudiment of the stipe, and on the outside an envelope of 

 hyphae. Where the rudimentary stipe passes into hyphae, at its upper end therefore, an 

 extremely active formation of new hyphae takes place, from which the pileus is 

 ultimately developed ; these hyphae grow close together and expand. The elements of 

 the whole of this rudimentary structure are closely confined within a definite limited 

 space, and the inner portion becomes separated off from the whole mass as the young 

 pileus. This rudimentary pileus enlarges by marginal growth and is enveloped in the 

 volva, which is the external portion of the rudimentary fructification and consists of 

 hyphae loosely intertwined. The volva continues to be developed from the hyphae 

 which were not directly used in the formation of the stipe, so that this envelope 

 surrounds the young fructification as a velum universale. Then the lamellae make 



De Bary, Aecidium abidinum in Bot. Zeit. 1879, pp. 828-843. 



