GENERAL SUMMARY 265 



In pure oxygen fruit-bodies shed their spores for several hours at the same 

 rate as in air. 



When a fruit-body is subjected to the vapour of ether or chloroform, 

 spore-discharge ceases almost instantaneously, but can be resumed when 

 the anaesthetic has been removed. A fruit-body of Lenzites betulina re- 

 covered its spore-liberating function after this had been inhibited by ether 

 vapour for a week. 



CHAPTER XI. The four spores on each basidium are discharged suc- 

 cessively. They leave the sterigmata within a few seconds or minutes of 

 one another. 



Each spore is shot out violently from its sterigma to a distance of about 



CHAPTER XII. The propelling force during spore-discharge seems to 

 be provided by the pressure of the cell-sap of the basidium upon the cell- 

 wall, and possibly by a similar pressure in the spore. On the discharge 

 of a spore, the sterigma breaks across but does not open. Spore-discharge 

 in the Hymenomycetes appears to resemble that in Empusa Grylli, and 

 may be said to be brought about by a jerking process, which may be con- 

 trasted with the squirting process of Empusa mnscas and the Ascomycetes. 



CHAPTER XIII. The specific gravity of spores can be determined 

 approximately by using heavy fluids contained in a counting apparatus, 

 the chamber of which is O'l mm. deep. The specific gravity of spores of 

 Amanitopsis vaginata was found to be nearly that of water, namely, 1-02, 

 whilst that of the much heavier Coprinus plicatilis spores proved to be 

 approximately 1-21. 



CHAPTER XIV. The size of spores can be measured with accuracy and 

 rapidity by using a Poynting Plate Micrometer. The apparatus has been 

 described. 



The average size of the spores of a fruit-body may differ considerably in 

 different fruit-bodies of the same species. This fact may well account for 

 the want of agreement of spore measurements as given by different 

 mycologists. 



CHAPTER XV. The rate of fall of spores in still air was determined for 

 the first time. A small piece of a fruit-body was placed in a vertically- 

 disposed compressor cell. The falling spores were observed with a hori- 

 zontal microscope and their rate of fall accurately recorded upon a revolving 

 drum. 



The first direct test of the applicability of Stokes' Law to the fall of 

 microscopic spheres in air has been carried out by determining the size, 



