ANATOMY OF FUNGI 47 



each other, cutting the spore up into quadrate or oblong 

 cells; this arrangement is described as muriform. Oospores, 

 the result of a sexual act, are always one-celled. The 

 female organ in the young condition is called an oogonium; 

 immediately preceding the act of fertilisation the greater 

 portion of the protoplasm contained in the oogonium 

 separates from the wall and forms one or several spheres, 

 each containing one or more nuclei ; these spheres are 

 termed oospheres or eggs ; after fertilisation the oospheres 

 become surrounded by a thick cell-wall, and are called 

 oospores. 



Spores vary in form from perfectly spherical or globose, 

 the rarest condition, through elliptical, by far the most 

 general form, to lanceolate and acicular or needle-shaped. 

 Some are stellate, others spirally coiled, etc. 



Spores are borne singly on the sporophores, but in coni- 

 dial forms it is by no means unusual for the conidia to be 

 produced in long necklace-like chains, when they are said 

 to be concatenate ; the conidia forming such chains become 

 free from each other at maturity. 



The hymenium of a typical species of Agaricus presents 

 the following different structures : 



(i) Basidia, or spore-bearing cells. Each basidium 

 consists of a single relatively large cell, usually more or less 

 clavate in form, and projecting from its free thickened apex 

 are four slender, spine-like bodies or sterigmata. Each 

 sterigma bears a single spore at its tip. Although four 

 sterigmata is the number most frequently present, in some 

 species the basidia bear only two sterigmata each. 



(2) Paraphyses, or sterile clavate cells, usually thinner 

 and shorter than the basidia, and more numerous. These, 

 with the basidia, are the only constant elements of the 



