328 XXIV. REPRODUCTION OF THE HIGHER FUNGI AND LICHENS. 



Dung-cultures so rarely fail to produce some of the AscobolicUe 

 that they may be considered the readiest means of obtaining 

 material for the study of the Discomycetous Ascomycetes. 



The small cups have a diameter of from ^ to i inch ; their 

 somewhat projecting base appears, according to circumstances, 

 dark brown or yellow. This colour often changes while under 

 observation especially when the culture is examined in early 

 afternoon and, by lifting the cover, a sudden change is induced 

 in the state of moisture of the material and its surrounding atmo- 

 sphere. It can then be determined that the dark masses, which 

 are spores, have been flung out of the sporangia. If the vessel is 

 not too high, microscopical examination of its cover will easily 

 show the Ascobolus spores clinging to it, singly or in little heaps. 

 The black heads of Pilobolus may similarly be clinging to the 

 glass cover. 



If we remove from the substratum a fructification of Ascobolus, 

 a portion of the mycelium upon which it arises will probably 

 accompany it. It is a brownish feltwork, formed of thick hyphae, 

 septate by cross-walls. We prepare between finger and thumb, 

 or in other fashion, delicate longitudinal sections of the fructifica- 

 tion, and examine i>t under the microscope. The foot, tapering 

 downwards, is formed of pseudo-parenchymatous tissue. The 

 segments of the hyphae are considerably swollen, rounded or poly- 

 gonal by lateral pressure, of relatively considerable dimensions, 

 but very poor in contents. Upwards, the cells of this foot 

 decrease in size, but increase in contents, up to the very dense, 

 richly protoplasmic sub-hy menial tissue. From the broadly 

 expanded sub-hymenial tissue arises the hymenium, formed of 

 asci and paraph yses, The foot and hymenium alike are sur- 

 rounded by a cortex, composed of globular, somewhat firm-walled, 

 elements. These elements, in the main arranged in but a single 

 layer, are not clearly delimited from the inner tissue of the foot. 

 The asci contain eight spores, ascospores, the walls of which are 

 at first colourless, then become violet to brown. Simultaneously 

 with this change of colour a beautiful tracery becomes visible, 

 brought about by a delicate striation of the cell-wall. Quite 

 characteristic is the colourless, usually unilateral, swelling, a 

 gelatinous appendage, which each spore possesses, and which is 

 especially visible upon the spores while still colourless. Study of 

 their development shows that here also the entire protoplasm of 

 the ascus is not used in forming the spores, and it is easy to find 



