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SCIENCE 



[N. S. Vol. XXXI. No. 794 



the shedding is an active process and that the 

 plants were still alive. These two species are 

 the only ones so far tested by the author for 

 germination after such a long period of drying. 



The spores are forcibly ejaculated from the 

 sterigmata and fall down from between the 

 gills or from the tubes. Thus spores of 

 Amanita vaginata are shot outward with an 

 initial velocity of 400 mm. per second to a 

 distance of about 0.2 mm. The terminal ver- 

 tical velocity of falling is about 5 mm. per 

 second, while the spore is moist, but it soon 

 becomes about 3 mm. as it dries. For most 

 other species with smaller spores the spores 

 are shot out for 0.5-0.1 mm. and the terminal 

 vertical velocity is about 1-2 mm. per second. 

 The horizontal discharge is so rapid that it 

 can not be seen even with the aid of the micro- 

 scope. 



The terminal vertical velocity is reached in 

 about one four-hundredth of a second. In 

 actual observation and experience, however, 

 the terminal velocity of fall is reached later, 

 owing to the fact that the spores lose water 

 rapidly by evaporation so that the velocity be- 

 comes reduced to one haK in some and one 

 third in others, the loss of water oceuring even 

 in a small compressor cell which contained 

 wet blotting-paper and a drop of water, owing 

 to the relatively high vapor pressure in the 

 small spores whereby moisture passed over by 

 distillation to the large drop of water. The 

 more rapid fall, however, takes place while the 

 spore is passing from between the gills or 

 from the tubes, in consequence of which there 

 is less danger of convection currents carrying 

 them to the wall where they would adhere. 



The mechanism of spore discharge in the 

 Hymenomycetes receives special considera- 

 tion. Several previous investigators have 

 stated that the spores are squirted from the 

 ends of the sterigmata by the bursting of the 

 latter under hydrostatic pressure. Dr. Buller 

 shows very conclusively that in the species 

 studied by him and probably in all the 

 Hymenomycetes this method of spore dis- 

 charge is impossible. His reasons are as fol- 

 lows: (1) The successive, not simultaneous, 

 discharge of the spores from a basidium. If 



the spores were squirted off, the basidium 

 v.ould lose its turgor after the discharge of the 

 first one and the others would remain at- 

 tached, (2) the absence of drops of liquid on 

 the ends of the sterigmata, (3) the apparent 

 closed condition of the sterigmata after dis- 

 charge, (4) non-collapse of sterigmata and 

 basidia as the spores disappear. While he is 

 not able to state definitely the mechanism of 

 discharge, owing to the very minute size of 

 the point of the sterigma, he arrives at a very 

 reasonable conclusion as to the mechanism. 

 It is that of the existence of a double wall at 

 the junction of the sterigma and the spore so 

 that endosmotic pressure in the basidium and 

 spore causes the rupture of the lateral waU 

 connecting the edges of this double wall. 

 This probably occurs somewhat in the same 

 manner as the sudden breaking of threads of 

 Spirogyra in consequence of the high endos- 

 matie pressure of adjacent cells after the mid- 

 dle lameUa of the wall has disappeared. 



The trajectory described by the spore from 

 the time it leaves the sterigma and follows its 

 vertical path of fall is called the " sporahola." 

 It was impossible to observe any portion of 

 the sporabola except the path of vertical fall, 

 since the velocity of discharge is so great, the 

 initial velocity of a spore on leaving the 

 sterigma being 40 cm. per second. The initial 

 velocity is determined from mathematical 

 formula, since the maximal horizontal dis- 

 tance of projection and the terminal vertical 

 velocity of fall are determined by actual ob- 

 servation. These being known by mathe- 

 matical formula, the sporabola can be plotted. 

 The sporabola is remarkable in that the hori- 

 zontal part passes with a very sharp curve 

 into the vertical part, and the total declina- 

 tion on the horizontal path is approximately 

 equal to the diameter of the spore. The very 

 rapid slowing down of the horizontal velocity 

 is due, of course, to the enormous friction 

 which the relatively large surface of the 

 minute spore offers to the air, and for the 

 same reason the vertical velocity is very 

 slow. Here is shown a very beautiful in- 

 stance of correlation to structure and means 

 for distribution. The gills of most agarics 



