66 ' BOTANICAL GAZETTE [JANUARY 
Coprinus comatus there were estimated to be 5,240,000,000 spores, which fell 
at the rate of 100,000,000 per hour; these spores have an average length of 
12.55, so that if they were arranged end to end, the spores of a single 
Coprinus fruit would extend a distance of 41 miles. Probably the most pro- 
ductive of all plants is the giant puffball, Lycoperdon gigantewm; in a fruit 
whose dimensions were 40 cm.X 28 cm.X 20 cm. there were estimated to be 
seven trillion spores. The advantage of having such enormous numbers of 
spores is evident, when it is realized that in Polyporus squamosus, for example, 
it is estimated that only about one spore in a trillion is able to develop into a 
lant. 
The most important contributions of the volume concern the fall of the 
spores. Ordinarily, spore fall cannot be observed by the naked eye, even 
though the spores are discharged at the rate of a million a minute, but Pro- 
fessor BULLER has shown that by the use of a concentrated beam of light, it 
is possible to observe the fall without the use of magnification. By this means 
there was made the surprising discovery that in the more xerophytic species, 
with leathery fruit bodies, vitality is retained for a number of years; specimens 
may be dried and moistened many times, each moistening resulting in a renewal 
of spore dispersal. In such forms it is obvious that the fruit bodies may 
collected and spore discharge studied at leisure. In two cases it was shown 
that the spores of fungi that had been kept dry for three years still retained a 
capacity for germination. By the use of ingenious methods devised by the 
author, the rate of spore discharge, which is so rapid as to be incapable of obser- 
vation by the microscope, was calculated with mathematical precision. In 
Amanita vaginata the spores are shot out horizontally with an initial velocity 
of 400 mm. per second, but so rapidly does the rate slow down on account of 
friction with the air,.that when they have reached a distance of 2 mm. from 
their original position, they begin to descend. The terminal falling velocity 
of a moist spore is about 5 mm. per second, and is reached in 0.04 secone. 
The trajectory described by the spore is somewhat unique in that it passes 
so sharply from horizontality to verticality, and to such a trajectory BULLER 
gives the name sporabola. In connection with these studies it is interesting a 
to note that the author has made the first test of the applicability of STOKES’S 
law to the fall of microscopic spheres in air. 
The anism of spore discharge receives attention, but is not certainly 
demonstrated, though it is shown that the spores are not squirted out by the 
bursting of the sterigmata under hydrostatic pressure. The author thinks 
that discharge is due to the rupture of lateral walls at the junction of the 
sterigma and the spore through the influence of endosmotic pressure. BULLER 
points out that the trajectory of the spore is admirably suited for effective 
spore discharge, for if the spores shot out much less than 2 mm. they might not — 
be fully freed from the gill whence they come, while if they shot out farther, 
they might be in danger of hitting the opposite gill. Butter appears 4 | 
to have solved the question as to the advantage of deliquescence in Coprinus. 
