THE PILOBOLUS GUN AND ITS PROJECTILE 63 



to be made. An inspection of the photograph shows that most of 

 the projectiles hit the window as if it had been a target. The local 

 aggregations of sporangia in the central part of the window were 

 caused by sporangia running together in the drops of cell-sap which 

 were shot on to the glass with the sporangia. 



The Range of the Pilobolus Gun. — Experiments on the range 

 of the Pilobolus gun have been recorded by Coemans ^ in 1861, 

 by Grove 2 in 1884. by myself ^ in 1909, and by Pringsheim and 

 Czurda^ in 1927. Coemans observed a maximum vertical range for 

 P. oedipus of just over one metre (107 cm.) ; Grove observed a 

 maximum horizontal range for P. Kleinii of 4 feet 2 inches ; 



1 observed a maximum horizontal range for P. longipes of 6 feet 



2 inches, whilst Pringsheim and Czurda observed a maximum 

 horizontal range for P. sp. (? P. crystallinus) of 2 metres (6 feet, 

 7 inches). All these records have been broken in a series of experi- 

 ments which I have made since 1909 and which will now be described. 



The vertical range of Pilobolus longipes and P. Kleinii was 

 determined with the help of the apparatus shown in Fig. 26. The 

 chamber A, made of beaver-board attached to a wooden frame and 

 painted black within, was so constructed that its upper part a, 

 which had a large round hole h in its roof, surrounded and enclosed 

 the upper half of the lower part b above which it could be raised 

 to various heights by inserting within it at its corners sticks of 

 various lengths such as those shown at I. To change a set of four 

 shorter sticks for four longer ones, the panel d was first removed, 

 the part a was then raised to the desired height, then the four 

 shorter sticks which had stood vertically between the corner frame- 

 posts of 6 and the roof of a were removed and the four longer sticks 

 were inserted in their place. To permit of a culture dish containing 

 dung balls bearing Piloboli (A, c) being put into or taken out of 



^ E. Coemans, " Monographic du genre Pilobolus, specialement etudie au point 

 de vue anatomique et physiologique," Mem cour. et des Sav. etrang. Acad. Roy. de 

 Belgique, T. XXX, 1861, p. 39. 



2 W. B. Grove, " Monograph of the Pilobolidae," The Midland Naturalist, 

 Birmingham, England, 1884, p. 16. 



3 A. H. R. BuUer, these Researches, Vol. I, 1909, p. 259. 



* E. C Pringsheim and V. Czurda, " Phototropische und ballistische Probleme 

 bei Pilobolus," Jahrb.f. wiss. Bot., Bd. LXVI, 1927, p. 873. 



