256 Vegetable Mortars. 



in the same group by Fries, is of very doubtful affinity, and at 

 present does not seem to be well understood. 



There are other fungi, however, which shoot out their fruit 

 elastically, sometimes the whole fruit-bearing cell being ejected 

 and sometimes the contents only. In the genus Ascobolus,* as 

 the name implies, it is the asci, with their included sporidia, 

 which are ejected, though only so far as to make the surface of 

 the hymenium rough with projecting cells, as may very readily 

 be seen with an ordinary pocket lens in Ascobolus furfuraceus, 

 which is extremely common on cow-dung, and may be known 

 by its greenish hue, while the sporidia themselves are of a 

 bright amethyst blue, and form a beautiful object under the 

 microscope. 



In other cases it is the sporidia which are ejected. Many 

 of our readers must have frequently observed, on handling one 

 of ike large orange-coloured Pezizai which are such an orna- 

 ment to our woods in autumn, or the washy brown kind 

 which abounds on hot-beds in spring, a cloud of dust arise 

 with a sudden jerk, and assume a kind of curve as if shot 

 from a gun. This is composed of the sporidia, which are 

 elastically ejected, the mechanism by which it is effected not 

 being thoroughly understood. In Sphwrim the process takes 

 place as effectually, though in general not as suddenly, and 

 Pringsheimt has shown that in bphceria Scirpi a little circular 

 aperture is formed at the tip of both membranes of the ascus, 

 making way for the explosion of the sporidia one by one. This 

 he believes arises from the pressure which the fluid contents of 

 the ascus exercise on its elastic membrane, kept in a state of 

 tension. In many fungi the mere contraction of the walls of 

 the perithecium or peridium, as the case may be, effects the 

 protrusion of the spores, which, if accompanied by a quantity 

 of mucus, form tendrils at the mouth of the perithecium. In 

 the higher fungi, as amongst many of the Mucedines, it is pro- 

 bable that one spore is pushed off by the formation of another 

 behind, and if so it is very possible that this may take place 

 with a force sufficient to assist in the dispersion of the spores. 

 In a few cases the fructification is liberated only by decay, but 

 this seems to be the exception rather than the rule. 



DESCRIPTION OP THE FIGURES. 



Fig. 1. Group of Sphcerobolus stellatus before the rupture 

 of the peridium, slightly magnified. 



Fig. 2. A single peridium, more highly magnified, showing 

 the inner peridium inverted, and attached to the tips of tho 

 laciniae of the outer peridium. 



* From o.<tk6s, a bladder, and $a\\u, I cast. 



f Jahrbuchcrfur vrittenchaftliche Botanik, 1857, p. 192. 



