20 OERSTED, ON THE AGARICINI. 



mushroom-bed in " Rosenborg " garden that this Fungus had 

 flourished. In the bed jDrepared for mushrooms it spread its 

 mycelium like a delicate cobAveb over the earth, and in the 

 same spot one could And receptacles of all sizes. It Avas thus 

 easy, by arranging the different stages of development in a 

 descending sequence, to form a series of steps Avhich gra- 

 dually led from the fully-grown spore-receptacle down to its 

 first rudiments, hardly perceptible as a white point. Under a 

 slight magnifying power this shows itself as a conical felted 

 body. This form is retained by the receptacle until it has 

 attained a size of l-2mm. The first rudiments of the 25ileus 

 begin now to be evident as a little globular expansion at 

 the point of the conical stem. At the beginning the pileus 

 grows uniformly at all sides, and the receptacle is therefore 

 at this stage regularly formed, as in Agarics in general.* 

 The expanded base of the stem passes quite gradually over 

 into the mycelium-filaments, which radiate towards all sides, 

 so that here the organ designated as a root by the older 

 mycologists is wanting.f Only when the receptacle has at- 

 tained the size of 4-8mm. does the jiileus begin to grow more 

 strongly at one side, and thus by degrees the horizontal 

 position is exchanged for the vertical. Since the stem, when 

 the pileus is first commenced, ceases altogether to grow, the 

 fully-grown receptacle is very short-stemmed. The pileus is 

 undulate, wavy at the margin, bulged or lobed, membranous 

 or half-pellucid. The receptacle is often compound and 

 formed of two receptacles growing together by the stems, or 

 of three or more united by their bases. 



For so far the observation of the development of the 

 receptacle offers no difficulties. These begin only when, by 

 the aid of the microscope, we would seek to account for the 

 relations of the earliest developmental stages to the organs of 

 fertilisation, and it was only after many unsuccessful trials 

 that I succeeded in making preparations which would serve 

 to give a distinct conception of these organs. The mycelium- 



dotus, by reason of its sbort-stalked or slalkless eccentrically attached 

 pileus, forms a subgenus amougst the brown-spored Agarici, analogous to 

 Pleurotus amongst the white-spored. Both subgenera likewise have this 

 in common, that they, almost without exception, include species which grow 

 on trees. The above-named species has been already described in 1690 as 

 Fungus alhus minimus trilohatus (Ray, ' Synops. method, stirp. brit.'). It 

 is figured (amongst other places) in Persoon's ' Observationes mycologicse,' 

 ii, t. V, f. 12, and twice in 'Flora Danica,' viz., t. 1073 (as Agaricus jjubes- 

 cens, Vahl), and t. 1586. 



* This condition has not escaped Persoon's attention (' Observ. myc.,' ii, 

 p. 46). 



t The present species is thus described by E. Fries, " radiculis nuUis " 

 C Syst. myc.,' i, p. 275). 



