CALCIUM CARBONATE IN DIPTEROUS LARVAE 621 
remains is reduced to a thin transparent larval cuticle. All 
this shows that the puparia of Acidia heraclei and 
of Agromyza are composed of a thin larval cuticle, the 
internal surface of which is lined and strengthened with a layer 
of calcium carbonate. As to the Dipterous larvae, like Myia- 
tropa florea, Hristalis tenax, L., Syritta pipiens, 
L., and others, the Malpighian tubes of which contain caleium 
carbonate in form of a granular suspension, I could not follow 
with the necessary precision the course of their calcareous 
excretion. It is possible that a certain portion is mechanically 
expelled from the body before the metamorphosis takes, 
place. On the other hand, it is certain that a good part of the 
stored calcium carbonate remains in the pupa and undergoes 
a similar process of dissolution which we have seen to occur 
in the Acidia and Agromyaza larva. In fact, the empty 
puparia of these flies are also internally lined with caleium 
carbonate and effervesce when immersed in dilute acid. It 
is evident then that in Dipterous larvae the calcium carbonate 
(in the form of small granules or calcospherites stored in the 
Malpighian tubes or in the cells connected with the fat body) 
remains wholly or partly within the body of the larva until 
the latter pupates. During the first day of the metamorphosis, 
when the last ecdysis takes place, this product of excretion 
(CaCOs) dissolves gradually in the perivisceral fluid of the 
insect. It then passes through the newly formed cuticle of 
the pupa into the ecdysial fluid which fills the space between 
the pupal and the last larval cuticle. Finally, when the ecdysial 
fluid is absorbed, the calcium carbonate remains as a deposit 
upon the internal surface of the puparium. 
This mode of elimination of an excretory product from the 
body of an insect, being connected with the process of moulting} 
may well be named ecdysia] elimination. 
5. HyporHEses AS TO THE ORIGIN AND FUNCTION oF 
Cancium CARBONATE IN THE Larvat Bopy. 
According to Valery Mayet (18, 1896) the calcium carbonate 
stored in the Malpighian tubes of Cerambyx larvae forms 
NO, 260 Tt 
