i86 RESEARCHES ON FUNGI 



that he has seen both in winter and summer in numerous generations 

 obtained in cultures ; and that the reason why Coemans did not 

 always find them in this species was that he, Coemans, had some- 

 times had P. Kleinii, which has no network, under his eyes instead 

 of P. crystallinus. Van Tieghem, in a diagrammatic illustration of 

 the network (Fig. 93), shows the top of a discharged sporangium 

 in the form of a black disc marked out with white lines. 



Still later Zopf,^ in a study of the parasites of Pilobolus, illus- 

 trated the supposedly normal fruit-bodies of P. crystallinus. He 

 shows not only a discharged sporangium with polygonal markings 



on its upper surface, but also intact fruit- 



B bodies bearing undischarged sporangia with 



^ similar markings. Subsequently, he repro- 



^ duced two of these illustrations in the form 



G) of wood-cuts in his text-book of mycology .^ 



Fig. qz. — Pilobolus My own studies of the patterns on the 



crystallinus A, sporangia of p. Kleinii, P. lonqipes, and P. 



upper view oi spor- x o -j j. 



angiiim showing a umbonatus have led me to the following con- 

 white network. B, . / 1 \ . u j.i. j. 

 spores. Copied by clusions : (1) the patterns are never present 



the author^ Jrom on sporangia seated on their sporangiophores, 

 Troisiime Memoire but only on discharged sporangia ; and (2) the 



(1876). Magnifi- 



cation, not given. patterns develop on discharged sporangia as 



these dry up and flatten down. I am there- 

 fore of the opinion that Zopf was in error in representing a pattern 

 on the undischarged sporangia of P. crystallinus. 



The netted pattern on a dried sporangium is due merely to the 

 ^VTinkling of the hemispherical sporangium-wall as this settles down 

 on the drying mass of spores. This mass, as it loses water by 

 evaporation, shrinks to less than one-half of its original volume. 

 The white Unes represented by Coemans and van Tieghem in their 

 drawings of Pilobolus crystallinus (Figs. 92 and 93) were doubtless 

 ridges around depressions. Sometimes, as I have observed in 

 a large flattened sporangium of P. Kleinii, the sporangium-wall 



^ W. Zopf, " Ziir Keiintniss der Infectionskrankheiten niederer Tliiere und 

 Pflanzen. No. IV. Einfluss von Parasitismus auf Zygosporenbildung bei Pilobolus 

 crystallinus," Nova Acta Acad. Cues. Leop. Nat. Cur., Bd. LII, 1888, Plate XXII, 

 Figs. 1-3. 



2 W. Zopf, Die Pilze, Breslau, 1890, Fig. 54, Nos. 2 and 3, p. 84. 



