34 



RESEARCHES ON FUNGI 



These liquids were contained in vessels filled with glass beads. 

 Next morning it was found that the fruit-bodies had developed 

 normal sporangia and stipes of normal length and that the average 

 width of the subsporangial swelling in ocular-micrometer divisions 

 for the fruit-bodies grown on water and on the 4-5, 9, and 18 per 

 cent, sugar solutions was 49, 38, 29, and 14 respectively. It thus 

 appears that the width of the subsporangial swelhng is determined 

 in part by the osmotic value of the substances dissolved in the water 

 permeating the substratum. 



Lepeschkin ^ washed off the " fat layer " from some young 

 fruit-bodies which had not yet developed subsporangial sweUings, 

 isolated the fruit-bodies from the mycelium, and then set half of 

 the fruit-bodies with only the basal swelling in water (normal apical 

 end in the air) and the other half of the fruit-bodies with only the 

 apical end in water (basal swelling in the air). Next day he found 

 that the fruit-bodies which had had the basal swelling in water had 

 subsporangial swellings of normal diameter (46 micrometer divisions), 

 whilst the fruit- bodies which had had their apical ends in water had 

 subsporangial swellings of much less than normal diameter (9-15 

 micrometer divisions).^ These results suggest that immersion in 

 water prevents the subsporangial swelling from developing to its 

 normal size. 



The Ballistics of the Projectile.— Link, ^ in 1809, was the first 

 to attribute the projection of the sporangium to its true cause, the 

 tension in the swelling below the sporangium ; and this explanation 

 was endorsed by de Bary ^ in 1866. The osmotic pressure in the 

 cell-sap of the sporangiophore just before the discharge of the 

 sporangium is effected has been measured by the writer {vide infra) 

 and has been found equal to a pressure of several atmospheres. 



AUen and Jolivette,* in the course of their studies of the helio- 



1 W. W. Lepeschkin, loc. citt, p. 424. 



2 H. F. Link, " Observationes in Ordines plantarum naturales," Magaz. d. Ges. 

 naturf. Freunde, Berlin, Bd. Ill, 1809, p. 32. He says : " Explosio fieri mihi 

 videtur, dum suprema pars stipitis buUata, sporangium inferne ambiens, contrahitur." 



^ A. de Bary, Morphologic und Physiologic der Pilze, Flechten, und Myxomyceten, 

 Leipzig, 1866, p. 146. 



* Ruth F. Allen and Hally D. M. Jolivette, " A Study of the Light Reactions of 

 Pilobolus," Trans. Wisconsin Acad., Vol. XVII, 1914, pp. 533-598. 



