THE SIZE OF SPORES 161 



from the following example, which gives the plate micrometer scale 

 figures obtained for the diameters of 100 fresh spores of Amanit<ypsi* 

 vaginata (Specimen III.) measured in water : — 



The average scale measurement for the spore diameters of 100 

 spores was found to be 40-905. The calibration figures for ten suc- 

 cessive distances of 10 //. each on a stage micrometer were as 

 follows : i 34-5, 36-1, 35-0, 351, 36-0, 34-5, 34-5, 35-4, 36-0, 34-5, whence 

 it was calculated that ^ = 3*51 plate micrometer scale divisions. The 



average diameter of 100 spores, therefore, = - ° = 11-65 ix. 



The Table on page 162 gives some of the results of measurements 

 with the Poynting Plate Micrometer. Each measurement given 

 is the average of 25 or 50 measurements of 25 or 50 spores respec- 

 tively. The last column gives the value Vl° n g ax is x short axis. 



Illustrations of all the spores in the Table are given in 

 Fig. 55. 



From the Table the general range in size of the spores of 

 AgaricineaB may be gathered. 2 The very large spores of Coprinus 

 plicatilis are about twenty-two times the volume of the very small 

 spores of Collybia dryophila. In all cases, however, and this 

 may be stated quite generally for the Hymenomycetes, the spores 

 are so small that they must fall in the manner indicated by Stokes' 

 Law, i.e. almost immediately after liberation (within a very small 



1 The differences between these readings are due to errors in the construction 

 of the stage micrometer, and not to any want of delicacy on the part of the Plate 

 Micrometer. 



2 The largest spores of any known Agaric are those of the exceptional Coprinus 

 gigasporus, which measure 28-30 x 14-16 fi. G. Massee, "A Revision of the Genus 

 Coprinus," Ann. of Bot., vol. 10, p. 123. 



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