194 RESEARCHES ON FUNGI 



during the flattening of the pileus, the surface of the gills for pro- 

 ducing ripe spores would be less during the spore-producing period 

 than it actually is and, as a consequence, fewer spores would be 

 produced. The transverse corrugations of the gills of Co'prinus 

 sterquilinus and of C. comatus, therefore, must be regarded as a 

 factor, although a minor one, in rendering the fruit-bodies efficient 

 as spore-producing organs. It may be added that the production 

 in young gills of corrugations which are eventually straightened 

 out during the expansion of the pileus is not limited to the two 

 species of Coprini just named, but is found in a number of other 

 Agaricineae. I have noticed it particularly in Laccaria laccata. 



The gills of Co'prinus sterquilinus, like those of all other Coprini, 

 are ageo tropic. To prove this, all that one requires to do is to fix 

 the opening pileus in such a position that, as it expands, it becomes 

 flattened out not in a horizontal plane but in some other plane 

 inclined at a considerable angle to the vertical. Under such con- 

 ditions, one observes that the gills do not respond to a geotropic 

 stimulus : they remain in the planes in which they have been placed 

 and do not turn downwards toward the earth. In not being 

 positively geotropic they therefore differ from the gills of Psalliota 

 campestris and of other Aequi-hymeniiferae. Coprinus sterquilinus 

 would gain nothing by having gills which were positively geotropic, 

 for without this reaction, as we shall see, the spores are discharged 

 in a perfectly successful manner. 



A few hours before the spores are to be shed the stipe grows very 

 rapidly in length, for it passes from a stage slightly in advance of that 

 shown in Fig. 97, A (p. 232), to the stage shown in the same figure 

 at C in the course of a single evening. The greatest rate of growth 

 observed in a large fruit-body was 3 cm. in 3 hours, or 1 cm. per hour.^ 



1 0. Brefeld {Untersuchungen ilber Pilze, Heft III, 1877, p. 61) states that in 

 warm weather the stipe of large fruit-bodies of Coprinus stercorarius, during the 

 last half of the stretching period, elongates at a rate of upwards of half an inch an 

 hour. Thus the stipe of C. stercorarius may grow in length as fast as, or even faster 

 than, that of C. sterquilinus. But the maximum rate of elongation of these stipes — 

 about 1 cm. per hour — is far exceeded by the maximum rate of elongation of certain 

 Phanerogams. Thus the stem of a species of Dendrocalamus — a bamboo — has been 

 observed to grow in length in 24 hours, 57 cm. at Buitenzorg and 91 cm. in a green- 

 house at Kew, i.e. at rates of 2-4 and 3-8 cm. per hour respectively {vide W. Pfeffer 

 Pflanzenphysiologie, Leipzig, vol. ii, 1904, p. 17). 



