THE ELECTRIC CHARGES ON THE SPORES 195 



charges of different strengths, whilst a certain number do not 

 become charged at all. 



By another arrangement of the commutator, it was possible to 

 reverse alternately the charges on the plates or to remove them. 

 By reversing the charges alternately a spore can be made to take 

 a zigzag path across the field like that shown in Fig. 68, B. By 

 successively charging the plates -\ — , 00. — h, 00, -\ — , &c, one 

 can make the path of a spore still more irregular (Fig. 68, C). 



Several other species beside Psalliota campestris were tested, 

 among them being Polyporus squamosus. In all cases the spores 

 behaved like those of the Mushroom, the majority appearing to 

 be charged, either positively or negatively. 



That the spores bear electric charges during their passage through 

 the air may be regarded as a physical fact of no apparent biological 

 importance. There seems to be no reason to suppose that in 

 nature the spores, in consequence of being electrified, settle on 

 one surface rather than another. It therefore appears improbable 

 that the charges are of use to the spores in enabling them to obtain 

 advantageous locations for germination. 



A further investigation as to the manner in which the spores 

 originally become charged and into the conditions which determine 

 the gain or loss of charges by them was thought unnecessary for 

 my present purpose. 



