THE PILOBOLUS GUN AND ITS PROJECTILE 59 



the sporangiophore begins to develop into a sporangium (Figs. 12, 



Fig. 23. — Pilobolus Kleinii, wild, on uii sterilised horse dung in 

 a culture chamber. Stages in the development of a fruit- 

 body and, in particular, of the subsporangial swelling : a, 

 basal swelling ; b, stipe ; c, sporangium ; d, subsporangial 

 swelling. A, in the afternoon : a tuber (trophocyst) has 

 begun to develop into a fruit-body : the tuber a is now to be 

 regarded as a basal swelling and its apical outgrowth 6 as a 

 stipe. B, at 6 p.m., a very short fruit-body : a sporangium 

 c has developed at the end of the stipe ; as yet there is no 

 trace of a subsporangial swelling. C and D at 12.20 a.m. 

 and E at 9 a.m., showing successive stages in the development 

 of the subsporangial swelling. Magnification, 27. 



6, 23, B, and 24, D). The sporangium attains its full size before 

 midnight. At first, it is orange owing to its content of orange- 



