CALCIUM CARBONATE IN DIPTEROUS LARVAE 617 
assumes a taxonomic importance and helps one to recognize 
these larvae and to differentiate them from the phytophagous 
larvae belonging to other families like Anthomyidae and 
Trypetidae, the fat body of which is devoid of calcospherite 
cells. 
3. CALCOSPHERITES IN THE MALPIGHIAN TUBES. 
The only case of the existence of calcospherites in the 
Malpighian tubes is that of the larva of Acidia heraclei, 
the celery-fly larva. On examining a living larva of Acidia 
gently compressed between the slide and coverglass, I have 
noticed that its body contains a number of large calcospherites 
similar to those of Agromyzine larva. J thought at first 
that the calcospherites of Acidia larvae were also formed 
in special cells connected with the fat body. The dissection 
of these larvae revealed that such was not the case; all the 
caleospherites were lying free in the lumen of the Malpighian 
tubes and especially in their terminal portions (Text-fig. 4, 
I and II, ¢.). The calcospherites of various sizes, from 8 pu 
to 140 in diameter, distend these tubes, which have the 
appearance of being composed of highly refractive beads. 
The calcospherites when small are very often double, i.e. with 
two or more central granules (Text-fig. 5, b, c, and d). The 
occurrence of the calcospherites in the Malpighian tubes 
(Acidia heraclei) and in the fat body (Agromyzinae) 
of the phytophagous Dipterous larvae demonstrates once 
more the similarity in the excretory function of these two larval 
organs, 
4, Kopystan Evimination or Cancrum CARBONATE 
DURING METAMORPHOSIS. 
All the foregoing shows that the larvae of a great number 
of Diptera contain in their Malpighian tubes, or in the cells 
connected with the fat body, a large quantity of calcium 
carbonate stored in the form of minute granules or large 
calcospherites. 
