VI. 



THE SPORE AND ITS DISSEMINATION. 



A work of this character would hardly" be deemed complete 

 without some reference to the above subject, which has moreover 

 a relation to some of the questions discussed, and particularly of 

 spore diffusion in the atmosphere. The largest spore is micro- 

 scopic, and the smallest known scarcely visible under a magni- 

 fying power of 360 diameters. Taking into account the large 

 number of species of fungi, probably scarcely less numerous than 

 all the flowering plants, and the immense number of spores which 

 some of the individuals produce, they must be exceedingly plen- 

 tiful and widely diffused, though from their minuteness not easy 

 to be discerned. It has been attempted to estimate the number 

 of spores which might be produced by one single plant of Lyco- 

 perdon, but the number so far exceeds that which the mind is 

 accustomed to contemplate that it seems scarcely possible to 

 realize their profusion. Recent microscopic examinations of the 

 common atmosphere* show the large quantity of spores that are 

 continually suspended. In these investigations it was found that 

 spores and similar cells were of constant occurrence, and were 

 generally present in considerable numbers. That the majority 

 of the cells were living, and ready to undergo development on 

 meeting with suitable conditions, was very manifest, as in those 

 cases in which preparations were retained under observation for 

 any length of time, germination rapidly took place in many of 

 the cells. In few instances did any development take place, 



* Cunningham, in " Ninth Annual Re port of the Sanitary Commissioner with 

 the Government of India." Calcutta, 187 2. 



