36 RESEARCHES ON FUNGI 



spores can be beautifully illustrated with an elongated balloon 

 as follows. A balloon which is 24 inches long and 6 inches wide 

 and having a density just exceeding that of air, is taken in the hand 

 and held with its long axis perpendicular ; and it is then allowed to 

 fall from rest. Almost immediately after its liberation, it turns 



FIG. 13. The balloon -gun for discharging balloons. A balloon is shown held 

 in position on the platform just before the slamming-board is released by 

 pulling the trigger. The base -board was 2 feet long. 



through a right angle and comes to place its long axis horizontally ; 

 and so directed the long axis remains until the balloon has reached 

 the ground. Such an elongated balloon, however liberated, always 

 quickly turns, just as does an elongated spore, until its long axis 

 comes into a horizontal position. 



When projected horizontally, toy-balloons filled with air or a 

 mixture of air and coal-gas have a trajectory exactly resembling 

 that which I have described for spores. 1 The simplest way of 



1 Vol. i, 1909. pp. 185-189. Figs. 64-66. 



