176 



RESEARCHES ON FUNGI 



t 



ornamented with minute crystals of calcium oxalate ; (2) that the 

 fringe of the sporangium-wall which overlies part of the gelatinous 

 ring, is more or less circular at its free margin (not extended radially 

 into broad rays),i is transparent, is largely or quite free from crystals 

 of calcium oxalate, and is colourless or tinged very faintly with 

 bluish-grey ; and (3) that the gelatinous ring extends radially from 

 the black portion of the sporangium more than twice the distance 

 of the fringe of the sporangium-wall. 



The fringe of the sporangium-wall of the dried discharged 



sporangium of Pilobolus umbonatus is so 

 characteristic for the species that by this 

 character alone one can readily distinguish 

 P. u7nbonatus from P. longvpes and P. Kleinii.. 

 In these two last-named species the fringe : 

 (1) instead of being circular at the free 

 margin, is siMt into broad radially-extended 

 rays (Figs. 33, 34, and 39 ; pp. 77, 78, 

 and 83) ; (2) instead of being largely or 

 quite free from crystals, is finely punctate 

 with evenly-spaced crystals, larger and smaller 

 crystals usually forming a sort of pattern 

 (Fig. 44, A, p. 88) ; and (3), instead of being 

 colourless, is distinctly brownish. 



As a sporangium which has been dis- 

 charged on to a glass slide dries up, the 

 umbo becomes more prominent (Fig. 105, K) 

 and at the same time the black part of the 

 sporangium-wall which covers the spores contracts considerably. 

 In some sporangia the contraction is uniform or almost so, so 

 that the dark wall remains smooth and devoid of depressions 

 (Fig. 105, I) ; whilst in other sporangia it is uneven, so that the 

 wall becomes dimpled or wrinkled. The wrinkles tend to take a 

 radial direction, so that the depressions between them are often more 

 or less triangular in outline (Fig. 105, J). 



1 It is possible that the part of the fringe corresponding to the rays of P. longipes 

 and P. Kleinii is broken away from the fringe at the time the sporangium strikes 

 an obstacle. 



Fig 



88. — Pilobolus um- 

 bonatus, after removal 

 of sporangium. The 

 dark, bluntly rounded 

 coluniella crowns the 

 subsporangial swell- 

 ing. Magnification, Gl. 



