438 



LECTURE XXVI. 



of our most remarkable Gastromycetes, Phallus impudtcus, the mycelium of which, 

 consisting of thick white threads growing in the soil of forests, presents essentially the 

 same appearance as that of the Agaric considered above. The fructification of the 

 Phallus arises as a spheroidal protuberance, composed of interwoven hyphse, on 

 one of the superficial branches of the mycelium. This protuberance while young 

 may be looked upon as a growing-point, the mass of tissue of which, however, while 

 growing up to the size of a hen's tgg, undergoes a differentiation quite other than in the 

 cases hitherto considered ; for although here also the polarity existing between the base 

 and apex of the structure is not entirely given up, still that process of growth which 

 may be compared with the elongation of a normal plant affects the fungal tissue, which 

 has passed out of the embryonic stage, in such a way that concentric layers of tissue 

 are differentiated. This occurs chiefly as follows : the most external layer, a, and 

 one lying deeper, /, attain considerable solidity, while the layer g situated between 

 them becomes transformed into a soft deliquescent jelly. The portion of tissue 



Fig. z6z.—Pediastrttm grauuletum, after A. Braun (400). A a disc consisting of cells which have grown together. 

 At g- the innermost membrane of a cell is just emerging : it contains the daughter-cells produced by the division of the 

 green protoplasm ; t various stages of division of the cells ; j ;* slits in the walls of cells already emptied. B the entirely 

 emerged inner lamella of the wall of the mother-cell {b) much swollen and containing the daughter-cells g, which are 

 actively swarming. C the same cell-family 4^ hours after emission, and 4 hours after the coming to rest of the small 

 cells— these have arranged themselves into a disc which is already beginning to develope into one like A^ 



marked st forms a hollow cylinder, the apex of which (x) is in connection with the 

 firm membrane i : in its interior, h, is a hollow cavity. The mass marked sp con- 

 sists of the spores or reproductive cells of the Fungus. When this complicated 

 differentiation of tissue (reminding one of the formation of certain berry-like or 

 plum-like fruits of Phanerogams) is completed, a final act of growth suddenly takes 

 place in damp weather. The stalk st now becomes extended in a few hours to 

 a length of 20-30 cm., its diameter being 3-4 cm. : by this the membrane a is 

 ruptured at the apex, while the membrane /, together with the mass of spores sp, 

 remain pendent from the top of the elongated stalk, and the base of the latter is 

 surrounded by the ruptured layers a, g and n, much as if by a broken egg-shell 

 The deviations from the normal type of growth prevailing in the vegetable kingdom 

 go still further in some other Gastromycetes, as in the genera Clathrus, Geasier, and 

 Crucibulujn (cf. Fig. 162). 



But even in the Algae, the majority of which follow the type of growth previously 



