24 



and southern slopes, however, the wind could not strike so hard, and 

 the spreading of, Flacherie toward the plain, therefore, took place com- 

 paratively slowly. Upon the eastern and western slopes, on account 

 of the lack of caterpillars, the conditions necessary for developing the 

 wilt were not present. 



A map of the place, sketched by Mr. Richardson (Fig. 2), which may 

 aid in understanding the description, is given herewith. 



Fig. 2. Experiment, Concord, Mass. A. Summit of hill, now cleared. B. 

 Northern slope, infested. C. Southern slope, infested. D. Eastern slope, 

 not eaten. E. Western slope, not eaten. F. Meadows. 



Five clusters were examined for comparison from the localities in 

 which Flacherie developed naturally. These were collected on a walk 

 through the forest district at the southern end of the hill, and from 

 different trees taken at random. The result was : 



Unfertilized eggs, . 

 Eggs with dead embryos, 

 apparently alive, . 



Cluster 1. 



jg \ =12.59 per cent., or about 12.5 per cent. 

 . 139 =87.41 per cent., or about 87.5 per cent. 



Total, . . . . 159 eggs. 



Unfertilized eggs, . 

 Eggs with dead embryos, 

 Eggs apparently alive, . 



Cluster 2. 



2l 



c. ? = 5.30 per cent., or about 5 per cent. 



143 =94.70 per cent., or about 95 per cent. 



Total, 



151 eggs. 



