47 
ON SPORE DIFFUSION IN THE LARGER 
ELVELLACEL* 
By Chas. B. Plowright. 
We have all frequently observed the clouds of sporidia, resem- 
bling puffs of smoke, which take place from the hymenia of the 
larger Pezizcs in a ripe condition. These jet-like expulsions of 
sporidia are apt to convey a very incorrect notion of the manner in 
which the fruit of this group of fungi is disseminated under ordi- 
nary circumstances. The jet-like clouds of smoke are the result 
of the rupture of a number of asci simultaneously. They occur 
only when the Peziza has attained full maturity, the asci being, so 
to speak, in a state of tension from their contents having attained 
the maximum amount of development. Under such circum- 
stances the giving way and consequent emptying of one ascus dis- 
turbs the equilibrium of those in immediate contact with it, and 
as they are lully matured, the slight concussion thus produced is a 
sufficient exciting cause, to render manifest the latent elasticity of 
their walls ; the measure of which elasticity being determined by 
the distance to which the cloud is expelled. 
On the 29th May, 1879, I gathered about one hundred speci- 
mens of Morchdla gigas^ Pers., and laid them out separately upon 
boards in my study. In the evening, as the rays of the setting 
sun fell obliquely upon them, I observed that all the older speci- 
mens were quietly and continuously diffusing their sporidia. Each 
sporidium was distinctly visible to the naked eye, floating in the 
air, twisting and turning in the sunlight. The head of each of the 
morells in question was surrounded by a cloud of sporidia extend- 
ing three or four inches above and around it. This cloud could 
only be seen in the oblique light against a dark background. 
When acted upon by a gentle current of air, such as would be 
produced by gently waving the hand, it swayed to and fro, without 
manifesting any tendency to become dispersed. The component 
sporidia were in constant motion, rising and falling, atid circling 
about, as if the law of gravity was a myth existing only in the 
imagination of philosophers, W hen the cloud was blown quite 
away by a more powerful air-current, it in the course of a few seconds 
reformed. The contents of each ascus could be seen to be sepa- 
rately ejected in a minute jet, consisting of a limited number of 
sporidia, which speedily became lost with the others forming the 
cloud. 
The phenomenon above described is interesting from a physio- 
logical point of view, as showing the capabilities of the unaided 
human eye. These sporidia measured only about one-Iiundredth 
of an inch in their long diameter, and five-one-thousandths of an 
* Read at the meeting of the Woolhope Clnb, Oct 8th, 1880. 
