Structure and Lrfe-history of the Holly-fly. 283 
As soon as it begins to feed on the mesophyll-cells the 
calcareous concretions form in the fat-body, and these 
become conspicuous when the body is examined by trans- 
mitted light as large, brightly-refractive objects. 
The mode of life of the free larva has been related in an 
earlier part of the present paper (pp. 259, 260). 
