a 
: nee 2 po itn 
ed the nearer it should approach the circular form, 
obvious, the greater would be the facilities for this pr > 
Physiology of the Gyropodiem coccineum. 59 
There is a mechanism worthy of notice in the construc- 
tion of eo peeiers It was necessary thet these should 
close in such a manner as effectually to exclude moisture, 
since this would destroy the seeds, or prevent them from 
being thrown out of their receptacle . Asingle valve, form- 
ing a part of the sphere containing the powder, would hard- 
ly afford sufficient security in this respect; and t nge 
would not possess strength and elasticity enough, to caus ; 
the valve to shut down close after several successiv 
ral 
and two valves, closing against each other, could not pro- 
duce such an aperture. But as the valves to this fungus 
are actually constructed, they not only secure the contents 
of the inner sack from the access of moisture, but on open- 
ing present an aperture of a polygonal form. At F, on 
the plate, i isa view of three sets of valves, taken from three 
all somewhat irregularly curved outwards, so that their 
convex sides are brought into contact ; and yet they are #0 
fitted to one another, that there is no interstice betwe 
them, when closed. This construction will also render ih 
aperture somewhat polygonal, when the valves open; or 
rather it will be a spherical polygon. By this construc- 
tion too, if PT mistake not, a greater degree of strength and 
elasticity, will be imparted to the valves: for from their 
centre, or greatest height above the surface of the sphere 
spose cating the head of the fungus, there is a gradual slope 
towards their extremities; which, as already remarked, 
it is not merely on a line connecting those extremities that 
they yield, but also along all that part of the envelope be- 
tween this line and the curve of the valve, and likewise in 
the valves themselves along their slopes, Are there not 
