CALCIUM CARBONATE IN DIPTEROUS LARVAE 615 
composed of numerous concentric layers surrounding a 
central or excentric granulated body and bearing some resem- 
blanee to starch grains. When the calcospherites are dissolved 
in dilute acetic acid there remains an albuminoid stroma 
consisting of caleoglobulin. Examined in polarized light, the 
caleospherites show a black cross. The calcospherites, or 
Harting’s corpuscles, have been well described by Nathusius 
(15, 1890), who found them in numerous animals and plants, 
and by Pettit (18, 1897) in cases of pathological ossification in 
mammals.t 
In insects the calcospherites were discovered simultaneously 
by Henneguy (8, 1897) and Giard (unpublished observations 
quoted by Henneguy). Henneguy found them in the larvae 
of Phytomyza chrysanthemi, Kowarz. According to 
this author each calcospherite of this larva is enclosed in 
a special hypertrophied cell of the fat body. The fat of these 
cells disappears completely, and all that remains of the cell is 
reduced to a thin protoplasmic layer and a small degenerated 
nucleus. The calcospherites still appear in the pupa, but they 
are absent in the adult flies, and Henneguy thought that the 
imagines which he examined were probably obtained from the 
‘normal’ larvae, i.e. ‘larvae devoid of calcospherites ’. 
Giard has observed similar calcospherites in the larvae of 
Phytomyza lateralis, Fall., which attacks the inflores- 
cence of Matricaria inodora. 
Personally I have found the calcospherites in the fat body 
of many Phytomyzine and Agromyzine larvae (Text-fig. 2). 
In all the species where the calcospherites are present they are 
to be found in every individual larva throughout its life. 
In this my observations differ from those of Henneguy and 
Giard, who considered the presence of calcospherites as 
abnormal and probably only seasonal. The cells which contain 
the calcospherites are always connected with the fat body, 
although they never contain droplets of fat. As a rule they 
he in alveolar spaces formed among the fat cells (Text-fig. 3). 
1 To these two papers the reader is referred for numerous observations 
and references concerning this subject. 
