26 RESEARCHES ON FUNGI 



cent, solution of sodium chloride caused water excretion to cease, 

 and even a 0-5 per cent, solution brought about a very much 

 diminished excretion.^ 



The fruit-body primordia (the red bulbils, c/. Fig. 2, A, p. 4), 

 if cut away from the rest of the mycehum in the evening and supphed 

 with water, develop into normal fruit-bodies during the night, and 

 the next morning it is found that water excretion from the sporan- 

 giophores has taken place normally. This shows that water 

 absorption and water excretion take place in Pilobolus in one and 

 the same cell.^ 



The water-excretion energy (the volume of the fluid excreted 

 from ten sporangiophores during one hour in divisions of the col- 

 lecting pipette 3) increases almost proportionally to the temperature. 

 It was found to be : at 0° C, 0-0 ; at 3°-4°, 0-2 ; at 18°, 1-9 ; 

 at 25°, 2-8 ; at 30°, 3-6 ; and at 35°, 4-5. At 0° C. the stipes do 

 not swell at their apex and there is no excretion. At 35° C. the 

 excretion is so great that it is not covered by the absorption of 

 water by the basal swelhng. An exposure to 35° C. for a few hours 

 results in so great a loss of turgor that the sporangiophores bend 

 and fall.4 



In the evening a tuft of Piloboh was set in a glass tube and the 

 air in the tube was replaced with pure nitrogen. The sporangio- 

 phores continued their development and next morning the excretion 

 of drops was found to have taken place quite normally. Oxygen 

 therefore appears to have httle or no effect on the development of 

 a fruit-body primordium into a mature fruit-body or on the energy 

 of water excretion.^ 



1 W. W. Lepeschkin, loc. cit., p. 413. ^ /j/^.^ p. 414. 



3 The volume of each division of the graduated pipette was 0' 03 cubic mm. 



* W. W. Lepeschkin, loc. cit., pp. 414-416. 



^ Ibid., p. 416. Verification of Lepeschkin's statement that fruit-bodies of 

 Pilobolus can develop from primordia to maturity without any oxygen supply 

 seems desirable. There is the possibility that a very small amoxmt of oxygen diffused 

 out of the substratum on which the fruit-bodies grew after his experimental tube 

 was closed. One evening I covered some primordia of Pilobolus longipes fruit-bodies 

 and a small mass of horse dung on which they were growing with liquidum paraffinum 

 (depth upwards of one inch). Next morning I found that a number of the primordia 

 had developed during the night into normal mature fruit-bodies. The presence of 

 the liquidum paraffinum doubtless much reduced the access of oxygen to the fruit- 

 bodies, but whether or not it cut it off completely is uncertain. 



