THE PILOBOLUS GUN AND ITS PROJECTILE 139 



The contracting sporangiophore, in addition to expelling from its 

 interior a large quantity of cell-sap, sometimes also expels the proto- 

 plasmic septum from the top of the stipe ; for, immediately after 

 observing the discharge of a ripe fruit-body in water on a sHde under 

 the microscope, I have occasionally found the septum, which is 

 easily recognised by its annular shape and its red colour, lying in the 

 water at some distance from the mouth of the collapsed sub- 



FiG. 67. — niobalu.s Kleiiiii. Three sporangia which were 

 shot away with the subsporangial swelling attached to 

 them. Magnification, 50. 



sporangial swelhng (Fig. 65, D-F). Furthermore, on examining 

 the drops which have carried away sporangia through the air, 

 immediately after they have settled on white paper placed on a table 

 to receive them, I have sometimes observed that the drops contain 

 a little mass of red protoplasm. There is therefore reason to suppose 

 that, when the Pilobolus gun is discharged, the sap rushes up the 

 stipe with such violence that it is apt to tear the protoi)lasmic 

 septum away from the cell-wall, thus making it possible for the 

 septum to be included in the large drop of sap which is expelled 

 from the subsporangial swelling and carries the sporangium through 

 the air. 



