Entomological Notes. 



311 



next year the indurated mass itself acts as a foreign body, and 

 there grow around if, in succeeding years, laj'ers which are all 

 more or less distorted, until finally we have a large knot, in which 

 it is quite impossible to detect the original lesion. 



In the beginning of the lecture, we divided diseases caused by 

 fungi into two general classes, tumors and blights. The latter is 

 by far the larger and more destructive, and more generally recog- 

 nized as caused by fungi. Of course the consideration of blights 

 on fruit-bearing plants should not be kept distinct from that of 

 blights on vegetables, for in a scientific point of view they are 

 very closely related. To describe in detail even a small portion 

 of the blights of cultivated plants would require several lectures, 

 and I can now call your attention only to two, which are common 



Fig. 14. Uncinula Spiralis. 1, 2, 3, 4, 5, 6 show the different stages 



of its development, 

 on grape vines, and let them serve as types, two large and very de- 

 structive orders'of fungi. The fungi to which I refer are found 



