BASIDIA AND THE DISCHARGE OF SPORES 37 



projecting a balloon horizontally forward through the air is to use 

 one's hands for the purpose. A spherical balloon 6 inches in 

 diameter cast by hand as hard as possible in a horizontal direction 

 travels rapidly forward for about 2 or 3 feet and then makes a 

 sudden sharp turn downwards, after which it falls with a slow 

 and even terminal velocity vertically downwards toward the earth. 

 The resistance of the air reduces the horizontal projection- velocity 

 of the balloon to zero in less than a second and, by the end of this 

 time, the balloon has ceased to be carried forward and is simply 

 falling under the influence of gravity. Thus the sporabolic 

 trajectory, which for a spore has a horizontal component only 

 1-0 2 mm. long, can be demonstrated on a large scale to an 

 audience of considerable size. 



The balloon-gun which I invented to save myself the trouble of 

 projecting the balloons forward with my hands was of very simple 

 construction (Fig. 13). It was made of wood and consisted of the 

 following parts : (1) a base-board 20 inches long and 8 inches wide, 

 (2) two straight upright arms, 8 inches high, (3) a platform for the 

 projectile, attached to the two arms, (4) a slamming-board, 15 inches 

 long and 8 inches wide at its base, hinged below to the base- board 

 along a median transverse line, movable about its hinges through 

 nearly a right angle, i.e. from the nearly horizontal position shown 

 in Fig. 13 to a vertical position, in the latter position projecting 

 7 inches above the top of the platform, (5) a strong spring attached 

 to the middle of the slamming-board and to the base-board, and 

 tending to bring the slamming-board into a vertical position, 



(6) a triangular trigger-board attached to the base-board, and 



(7) a trigger attached to the trigger-board, passing upwards through 

 a slot in the centre of the slamming-board, and provided above 

 with a catch. In Fig. 13 the catch of the trigger is holding the 

 slamming-board down. 



The balloon to be used as a projectile was set on the top of 

 the platform with one side projecting toward the slamming-board ; 

 and it was held in position very lightly by pressure above applied 

 with a finger. The gun was then fired by pulling the trigger. 

 The movement of the trigger released the catch, whereupon the 

 slamming-board was caused by the spring to swing sharply through 



