THE VIOLENT PROJECTION OF SPORES 



135 



Coprinus and of many other genera goes, are never shot off simul- 

 taneously. I have also not been able to obtain any evidence that 

 the spores are projected forwards owing to ejaculation of the contents 

 of the basidia. The mechanism of spore-discharge, however, will be 

 discussed more conveniently in the next chapter. 



Several methods have been used to determine whether or not the 

 spores are shot off the sterigmata. The first one, which seemed for 

 some time to give convincing evidence of spore-projection, led to the 

 discovery of an unexpected optical illusion. 



Method I. The first method employed for observing spore-fall 

 microscopically was that of placing hymenial surfaces in vertical 

 planes and observing them from 

 above with an ordinary upright 

 microscope. 



Through the middle of some 

 of the hymenial tubes of a freshly 

 grown fruit- body of Polyporus 

 squamosus, a transverse section 

 1-2 mm. thick was made (Fig. 47). 

 This was then placed on a glass 

 slide, covered with a cover-glass, 

 and looked down upon from above 

 with the low power of the micro- 

 scope. Immediately the remark- 

 able fact was observed that the spores were apparently being shot 

 outwards from the hymenium towards the middle of the tubes. 

 Apparently one could see them taking part of their curved and out- 

 ward course through the air. They were also seen to settle below on 

 the glass slide on the average at a distance of 0'1-0*2 mm. (6-20 

 times their own length) from the hymenium. In this way the spores 

 collected in a zone about 0'5 mm. wide around the base of each tube. 

 In the course of a few minutes I watched the discharge of hundreds 

 of spores. Not only to myself, but to others, the apparent bombard- 

 ment of the spores into the lumina of the tubes seemed to afford 

 clear and convincing proof of the violent projection of the spores 

 from the basidia. 



Similar observations to those just recorded were then made upon 



FIG. 47. Diagram to show the shape of 

 a transverse section through the hy- 

 menial tubes of Polyporus squamosus. 

 About 6 times natural size. 



