THE SPHAEROBOLUS GUN 33* 



were somewhat larger and more vigorous than mine grown on an 

 old board. Also it must be noted that, whereas I had at my dis- 

 posal relatively few fruit-bodies, she was able to experiment with 

 many hundreds. 



On account of the large size of the fruit-bodies of Sphaerobolus 

 stellatus var. giganteus, one might have expected that this fungus 

 would shoot its projectiles higher than S. stellatus or S. iowensis ; 

 but, as the Table shows, it did not do so. The failure of S. stellatus 

 var. giganteus to beat its competitors' may well have been due to the 

 fact that, as Miss Walker states, S. stellatus var. giganteus did not 

 form basidiocarps in sufficient number to make a satisfactory test. 



In the experiments with Sphaerobolus iowensis, the counted 

 number of projectiles was only 40, but three of them were shot to a 

 height of 3-5-4-0 metres. This suggests that, if as many pro- 

 jectiles had been shot away by S. iowensis as by S. stellatus, a still 

 greater height of projection for S. iowensis might have been recorded. 



If every one of the fruit-bodies in Miss Walker's experiments 

 with Sphaerobolus stellatus had discharged its projectile vertically 

 upwards, it is probable that some of them would have been shot to 

 an even greater height than 4 metres 40 cm. ; but this record is 

 sufficient to indicate the marvellous efficiency of the Sphaerobolus 

 gun. 



The horizontal range of Sphaerobolus stellatus and of S. iowensis 

 was also investigated by Miss Walker. 1 As a result of a relatively 

 small number of experiments, she found that both these species 

 can shoot their projectiles somewhat farther than 5 metres. The 

 maximum horizontal range 2 observed by her for S. stellatus was 

 5 metres 5 cm., or approximately 17 feet 3 inches. As we shall 

 see shortly, working with the same species, I have observed an even 

 greater horizontal range than this, namely, 18 feet 7 inches. 



An Artificial Method for Causing a Sphaerobolus Gun to Dis- 

 charge its Projectile. — In 1870, Pitra 3 discovered that, some time 

 after a Sphaerobolus fruit-body has opened stellately and just 



1 L. B. Walker, "The Development and Mechanism of the Discharge in Sphaero- 

 bolus iowensis and S. stellatus," 1927, loc. cit., p. 158. 



2 L. B. Walker, in litt. 



3 A. Pitra, " Zur Kenntnis des Sphaerobolus stellatus,'" Bot. Zeit., Bd. XXVIII, 

 1870, pp. 702-703. 



