1 84 



RESEARCHES ON FUNGI 



this account, in determining the width-ratio of fruit-bodies of any 

 species of Pilobolus, it is advisable to use wild fruit-bodies obtained 

 from their natural substratum. Unfortunately, the sporangia of 

 Pilobolus Kleinii shown at B in Fig. 91 were obtained from a pure 

 culture. Had they been obtained from a wild culture, it is possible 

 that their average width-ratio would have been slightly smaller, 

 perhaps f instead of f , as wild fruit-bodies of P. Kleinii with a 

 width-ratio of about f have been observed. 



In concluding this Section, we may enquire to what extent, if 



Fig. 91. — Diagram illustrating a study of the ratio of the width of the sporangium 

 to the width of the subsporangial swelHng in three species of Pilobolus. Each 

 fruit-body is shown in top view ; the black area represents the sporangium, the 

 pale area the subsporangial swelUng. A, five wild fruit-bodies of Pilobolus 

 longipes (average width-ratio approx. f). B, five fruit-bodies from a pure 

 culture of P. Kleinii (average width-ratio approx. |). C, a wild fruit-body of 

 P. umbonatus (width-ratio ^). Magnification, 30. 



any, the patterns that can be found on the dried discharged sporangia 

 of certain Piloboli are of diagnostic value. 



Coemans,! in 1861, observed some curious markings on the 

 sporangium of Pilobolus crystallinus (Fig. 92). He says : " In 

 Pilobolus oedipus the tint of the coloration is uniform, but in P. 

 crystallinus it sometimes exhibits beautiful hexagonal patterns 

 which have a close analogy with the hexagonal cells of the choroid 



^ E. Coemans, " Monographic du genre Pilobolus Tode, specialement etudie au 

 point de vue anatomique et physiologique," Mem. cour. et des Sav. etrang. Acad. roy. 

 de Belgique, T. XXX, 1861, pp. 23-24. 



