254 



APPENDIX. 



[No. XV.c. 



drawing of a fungoid growth as observed by my father on an Aphis 

 vastator. On plate 4, amongst other kinds of fungi, is a parasitic fungus 

 on the leg of the Aphis vastator. At page 77 of the same work he writes : 

 " Doubtless the fungi exercise an important influence upon the progress of 

 the disease, although they most assuredly have not the power of producing 

 it. In fact, they never make their appearance until the potato plant has 

 been previously damaged, and until some portion of it is already dead." 

 And again, at page 122 : " There appears to me to be a very close relation 

 between the injury committed by the aphides and the appearance of fungi ; 



FIG. 14. 



Resting-spores of the Potato Fungus within an Aphis at A, B, c, enlarged 20 diameters. The same 

 resting-spores enlarged to 160 diameters on right-hand^margin. (From one of Mr. Smee's 1845 

 preparations.) 



B 



I * 



FIG. 15. 



Resting-spores of the Potato Fungus within the cellular tissue of Potatoes. A. From the stem. 

 B, c. From the tuber, enlarged 160 diameters. (From one of Mr. Smee's 1845 preparations.) 



for in numerous cases where I have observed fungi on the leaf, I have also 

 noticed aphides on the plant. 



" It is also a singular fact that there is a word in the Hebrew language 

 which means blight and mildew collectively, meaning thereby aphis and 

 fungus." 



In 'Instinct and Reason/ p. 261, Mr. Smee deduced the following 

 law of the ravages of the aphides : 

 " 1. Aphides feed on living plants. 



2. Aphides come first upon healthy plants. 



