378 



ORGANOGRAPHY. 



The spores, as we have just mentioned, may be either naked, 

 or enclosed in cases. We will investigate these two structures 

 separately. The simplest form of the former is seen in such 

 Fungi as Torula, Fenicillium {fig. 5), and Botri/tis ( fig. 6) ; where 

 one or more cells placed at the ends of simple or branched fila- 

 ments springing from the mycelium, are transformed into spores. 

 The term conidia has been used to distinguish certain forms of 

 stalked spores which thus arise from the mycelium : these co7iidia 

 may be regarded as a fourth kind of reproductive organ. Their 

 nature is at present but imperfectly ascertained ; they appear 

 physiologically to be analogous to thegonidia of Lichens. 



In other Fungi which have naked spores, or exospores as they 

 are sometimes termed, the reproductive apparatus upon which 

 they are placed is of a much more complex structure. That 

 of the common Mushroom {Agaricus campestris) {fig. 827) 



Fig, 827. 



Fig. 828. 



Ji^'flf. 827. Vertical section of the common Mushroom (Agaricus campes- 

 tris). my. Mycelium, vol. Remains of volva. si. Stipe, an. Annulus. 

 h. Hynienium with its lamellce, la. p. The pileus. Fig. 828. Trans- 

 verse section of portion of a lamella of Agaricus. bas. Basidia, each 

 hearing at its apex four spores, spo. a and b. The four spores sepa- 

 rated from the basidia. cys. Cystidia or sacs containing granular 

 bodies. 



may be taken as an example. The fructification is here first de- 

 veloped in a hollow round body, called the volva, which arises 

 from the mycelium, my; as the fructification becomes matured 

 it breaks through the volva, and the following parts may then 

 be seen, namely, a cap-like body, called the pileus, p, placed on 

 a stalk or stipe, st, and at the base of which are the remains of 

 the volva, vol. On the under surface of the pileus a number of 

 vertical plates or laminse are situated, which radiate from the 

 centre towards the circumference, these are the lamellcB or gills, 

 la ; they constitute collectively the hymenium, h, upon which the 

 spores are arranged. The hymenium is at first enclosed in a 



