138 



RESEARCHES ON FUNGI 



This phenomenon is due in part to the enormous pressure to which 

 the cell-wall is subjected by the cell-sap and in part to the cell- wall's 

 wonderful elasticity. 



The cell-sap which is expelled from the sporangiophore, when this 



contracts., issues from the circular 

 mouth of the subsporangial swell- 

 ing as a continuous jet which 

 immediately breaks up into several 

 separate drops. All these drops, 

 which are shot some distance, can 

 be readily caught on a sheet of 

 glass placed a few inches in front 

 of a fruit-body just before it dis- 

 charges its sporangium (Fig. 66). 

 The largest drop is formed at the 

 top of the jet, has the greatest 

 momentum, travels farthest, from 

 the first adheres to the under 

 wettable gelatinous side of the 

 sporangium, and carries off the 

 sporangium through the air in the 

 manner shownin Fig. 74, A (p. 151). 

 The other smaller drops are formed 

 from the jet in succession under 

 the first drop, are not so violently 

 expelled as the first drop, have 

 less momentum, and fall much 

 nearer to the sporangiophore which 

 has discharged them. Direct 

 evidence that the range for the 

 smaller drops is not nearly so 

 great as for the larger drop is afforded by the fact that, when fruit- 

 bodies look upwards and a glass plate is placed above them at 

 greater and greater heights as in a set of experiments aheady re- 

 corded,! after a certain height the only drops which strike the plate 

 are those which bear sporangia. 



1 Vide pp. 63-66. 



Fig. 66. — Pilobolus longipes. A-E,five 

 sporangia and the cell -sap shot 

 away from five fruit-bodies, after 

 they had struck a sheet of glass 

 held obliquely a few inches in front 

 of the fruit-bodies and after the 

 sap had dried up. The jet of cell- 

 .sap, on being squirted out from the 

 top of the subsporangial swelling, 

 broke up under the influence of 

 surface tension into a series of 

 drops. The largest drop travelled 

 with the sporangium to the greatest 

 distance. The smaller drops trailed 

 behind the drop attached to the 

 sporangium. Magnification, 2 • 6. 



