66 RESEARCHES ON FUNGI 



or not any sporangia had been shot up as high as the sheet of 

 glass or the beaver-board sheet holding the glass by simply examining 

 the under surfaces of these structures and noting whether or not 

 any sporangia had become attached there. As a rule, not more 

 than one experiment was made on any one day. 



In a series of experiments in which the top of the experimental 

 chamber was raised by successive increments (usually of 6 inches each) 

 from 3 feet to 6 feet 6 inches, it was found that the sporangia of Pilo- 

 bolus Kleinii and of P. longipes were shot from the top of the dung- 

 baUs vertically upwards : in considerable numbers to a height of 4 feet ; 

 in smaller numbers to a height of 5 feet ; and in still smaller numbers 

 to a maximum height of 6 feet • 5 inch. We may conclude, therefore, 

 that both P. Kleinii and P. longipes can shoot up their sporangia 

 to a maximum height greater than the average height of a man. 



In one experiment with P. Kleinii, the total number of sporangia 

 which were shot upwards from the top of the dung-balls to a height 

 of 5 feet 6-5 inches exceeded one hundred and twenty. Of these 

 sporangia fifteen had struck and stuck to the plate of glass (Fig. 26, 

 F, i) and over one hundred had struck and stuck to the sheet of 

 beaver-board {h) which held the glass and covered much of the hole 

 in the roof of the chamber. 



The total number of P. Kleinii sporangia which were shot up 

 to a height of 6 feet • 5 inch in the course of three successive daily 

 experiments was twenty. All of the twenty sporangia were found 

 to be of the largest size ^ and, from the unusually large diameters 

 of the haloes of precipitated matter by which they were surrounded, 

 it was evident that each one of them had been carried from its 

 sporangiophore to the roof of the experimental chamber by a very 

 large drop of expelled cell-sap. That the largest Pilobolus projectiles 

 should be shot to the greatest height was to be expected from 

 dynamical considerations ; for, the initial velocities being equal, 

 the larger the projectile, the greater is its momentum when shot 

 away and the higher will it be carried upwards through the air. 



From the equation : 



v^ = 2gs 



where v = the initial velocity, g = the acceleration due to gravity, 



1 One of them had a diameter of 0-54 mm. 



