CH. XXXVIII. ] 



CONCLUSION. 



337 



has two inconceivably fine cilia or vibrating hairs, by 

 which it can propel and guide itself over any moist 

 surface. The large spores of the putrefactive fungus of 

 lettuces, Peronospora Schleideniana, Ung., are shown at C ; 

 others of the putrefactive fungus of clover P. exigua, 



X-IOO 



FIG. 142. 



Foot of house-fly, with the spores of various parasitic fungi. 

 Enlarged 100 diameters. 



W.Sm., at D ; and the spores of the smut fungus of 

 grain, Ustilago carbo, Tul., at E. 



Every one who has walked amongst potato plants must 



have noticed the small green fly or plant-louse, Rhopalosi- 



phum dianthi, Schrank, shown, the natural size, at B, Fig. 



143. Some of the female lice possess wings, as shown, 



Z 



