Mabch 18, 1910] 



■SCIENCE 



421 



some half a dozen species. A. campestris re- 

 sponds in two ways to the influence of gravity 

 — (1) the adjustment of the pileus in a hori- 

 zontal position by the negatively geotropic 

 stem, and (2) the finer adjustment of the 

 gills by their positive geotropism. These two 

 adjustments he speaks of as the coarse and 

 fine adjustments, the positive geotropism of 

 the gills placing them in a perpendicular 

 position with reference to the earth in case 

 the pileus should be slightly tilted from the 

 horizontal. 



Polyporus squamosus responds in four ways 

 to the influence of gravity — (1) the negative 

 geotropism of the stem after the initiation of 

 the fruit body under the morphogenic influ- 

 ence of light, (2) growth of the pileus parallel 

 to the earth's surface, (3) growth of the 

 pileus with a symmetry suited to the position 

 of the stipe, (4) growth of the hymenial tubes 

 downward. Agaricus campestris is indifferent 

 to light, while the fruit body of Polyporus 

 squamosus is only initiated under the influ- 

 ence of light. The difference between the two 

 ' species in the number of responses made to ex- 

 ternal stimuli, the author says, is correlated 

 with the fact that one fungus grows on a tree 

 and the other on the ground. While this cor- 

 relation does exist it does not wholly explain 

 the fundamental difference in behavior. One 

 must take into consideration the difference in 

 the origin of the plant parts, as well as the 

 necessity of a permanent position of the 

 stratum of tubes compared with the change in 

 an agaric, provided the pileus has a general 

 horizontal position, since the gills may de- 

 scend or ascend from the stipe as the margin 

 of the pileus is elevated and yet spore fall may 

 not be interfered with. 



The number of spores produced by a single 

 fruit body was estimated in several species 

 and the enormous number probably far ex- 

 ceeds the estimates and shows how prolific 

 these plants are. An individual of Agaricus 

 campestris produces about 2,000,000,000 spores, 

 Oorpinus comatus about 5,000,000,000, Poly- 

 porus squamosus about 11,000,000,000, and an 

 individual of Lycoperdon giganteum, 40 X 28 

 cm. (16 X 11 inches) about 7,000,000,000,000. 



Single fruit bodies of some plants shed spores 

 at the rate of 1,000,000 a minute, and this may 

 be kept up for several days. Notwithstanding- 

 this enormous prolificness the waste is enor- 

 mous because of the small chance of a spore 

 being able to produce a new plant. He esti- 

 mates that in Polyporus squamosus, consider- 

 ing also the perennial character of the mycel- 

 ium, about one spore in 1,000,000,000,000 has 

 a chance of starting a new successful cycle. 

 The spores are sometimes shed in such vast 

 numbers that they can be seen in clouds float- 

 ing away from the plant. A species of Poly- 

 porus squamosus which was growing in a 

 greenhouse shed such vast numbers that, when 

 one entered in the morning and at other times, 

 the air was so filled with spores it appeared as 

 if some one had been smoking there. This 

 continued for thirteen days and the plant 

 continued to shed spores for three weeks. 

 The spore-fall period varies in different indi- 

 viduals of a species. It was determined for 

 several • species, and the following examples- 

 are given : For Coprinus plicaiilis a few hours, 

 Agaricus campestris two to three days, Poly- 

 stictus hirsutus five days, Lenzites helutina 

 ten days, Polystictus versicolor sixteen days, 

 Schizophyllum commune sixteen days, Poly- 

 porus squamosus three weeks. 



One of the remarkable discoveries is the 

 fact that many xerophj^tic fungi which have 

 been preserved dry for several months or 

 years may be revived by moistening, when 

 spore fall will be resumed and continue for 

 several days or weeks, even after the plants 

 have been dried and revived several times in 

 succession. Thus Corticium loeve revived 

 after one year shed spores, Phlehia pileata 

 (Phlehia strigosozonta) after two years and 

 eight months, Polystictus versicolor two years, 

 P. hirsutus three years, Schizophyllum com- 

 mune two years, Trogia crispa four months, 

 Lenzites helutina three years, Marasmius 

 oreades six weeks, Collyhia dryophila one 

 week. Spores of Daedalea unicolor and 

 Schizophyllum commune, after the fruit bod- 

 ies had been kept dry for three years, shed 

 spores which were capable of germination as 

 determined by test. This demonstrates that 



