622, D. KEILIN 
a real reserve substance which has an important function 
during the metamorphosis. Just before the last moult the 
larvae, which form galleries in the wood of pine-trees, disgorge 
the calcium carbonate, with which they cover the walls of 
the galleries, thus protecting the pupae from the sap of the tree 
and preventing the invasion of the galleries by fungi. The 
opercula which close the galleries are also formed from calcium 
carbonate of the same origin. 
Vaney (19, 1900; 20, 1902) also speaks of calcium carbonate 
stored in the Malpighian tubes of Stratiomys larvae as a reserve 
substance. 
According to Henneguy (8, 1897) the calcospherites of A gro- 
my za larvae, which he wrongly supposed to be only seasonal, 
are probably attributable to the special conditions of feeding 
of these larvae during the autumn. 
Pantel (17, 1914) considers the calcium carbonate as an 
ordinary product of excretion, which is probably due to an 
excess of calcareous substances present in the food of the lar- 
vae. The formation of calcium carbonate in the larva of 
Hristalis, Ptychoptera, and Stratiomys, which 
live in putrefying organic substances, and in the parasitic 
Dipterous larvae, reminds one somewhat of the calcareous 
excretion observed in several other organisms. Calcospherites 
are known, for instance, to exist in the parenchyma of Cestodes 
and in the excretory tubules of Trematodes, and, according to 
Burian (4, 1912, pp. 401-5), these calcospherites are derived 
from the neutralization of carbon dioxide. He explains thus 
how the parasitic worms, which live in a medium which already 
has a high CO, content, get rid of the CO, derived from thew 
respiration. 
According to Combault (5, 1909), the crystals of calcium 
carbonate, which fill the calciferous or Morren glands of 
Oligochaetes, are also products of the neutralization of the 
carbon dioxide which passes from the blood circulating in the 
lamellae of these organs. 
The neutralization of the CO, of respiration and the forma- 
tion of calcium carbonate was also shown by Bohn (2, 1898) 
