Vegetable Mortars. 253 



certain area was studded with little jet-black spots, as if some 

 insect had deposited its excrement upon it, and, as in the 

 former case, chips, plant-labels, and other lifeless bodies within 

 the limits were similarly spotted. The first impression, on 

 receiving specimens, was that I had to deal with some species 

 of Perisporium unusually indifferent as to the matrix on which it 

 grew. Instructed, however, by the experience of the former 

 case, and informed that a thick coating of fresh dung had 

 lately been spread over the surface, I fancied that the solution 

 might be found in the generation of some explosive fungus in 

 the dung, and further inquiry soon elicited that a species of 

 Pilobolus was the head and front of the offence. 



The extraordinary force with which these sporangia are 

 discharged, and the distance in consequence to which they are 

 sent, being quite equal, if we may compare small things with 

 great, to that of a shell discharged from a small mortar, it 

 may not be uninteresting to give some account of these fungi, 

 and the more so, because I am not aware that the. fructification 

 of the first has hitherto been figured. 



Sphcerobolus stellatus,* though, perhaps, not very generally 

 observed, as it is not very conspicuous unless fully expanded, 

 is widely diffused, and is to be met with not unfrequently on 

 soft decayed sticks in damp woods. It occurs also on all 

 kinds of decayed vegetable substances in conservatories, pro- 

 vided they are not too moist or inclined to putrescence ; but I 

 have seen it nowhere in such abundance and perfection as on 

 old heaps of sawdust about saw mills in Wales, where it some- 

 times occurs in sheets several feet in width. When unex- 

 panded it looks like little grains of white mustard-seed 

 partially covered with a delicate down, and more or less 

 immersed in the matrix. These globular bodies, the outer 

 coat of which consists of several concentric layers of cells 

 differently arranged, some of which are colourless, and some 

 tinted with orange, contain a tough hyaline lining membrane 

 immediately surrounding the single globose sporangium. 

 When all is ready, the outer coat splits nearly half-way down, 

 into a few stellate divisions, and at the same time the lining 

 membrane is inverted with such force as to shoot out the 

 sporangium, the membrane itself adhering to the divisions of 

 the peridium. The action is, in fact, precisely the same 

 as that of a body tossed from a blanket held at the four corners. 

 The disposition of the cellular tissue of the peridium will be 

 seen from the subjoined figure. The sporangium itself consists 

 of a dark outer coat immediately covering a mass of colourless 

 cells, radiating towards the centre, the innermost of which, or 

 at least a certain number of privileged individuals, produce at 

 * From fffyaipa, a sphere, and /3c£\\w, I cast. 



