192 Journal of the Asiatic Society of Bengal. [ May, 1906, 
the larva. The Sponge grows very rapidly and the larva is soon 
in danger of being engulphed in its substance. The tube is there- 
fore lengthened, in order to avoid this catastrophe and to secure 
communication with the exterior, he process may continue until 
the tube is over an inch in length, its diameter increasing with the 
growth of its maker, Theinternal apertnre becomes practically closed 
to make no difference to the latter, which lives on in its tube. 
Theentrance to the tube may project some little distance beyond 
the worn surface of the larva’s dead host 
The larva does not eat the Sponge but feeds on minute 
stance of the sponge, and can with difficulty be separated from it. 
At first sight it would appear that the presence of a foreign 
body such as the tube of this Chironomus larva in the interior of & 
living organism would be necessarily harmful to that orga 
. n 
remains coherent after the death cf the cells of the Spong' 
serving as a nest for the gemmules which it retains. The tubes 
of the Chironomus larva in preserving this 
coherence by binding the the ‘substance out 
r is tough and persistent, The larva, 
e larva does not pupate in the Sponge. 
Col. Alcock * has drawn my attention to certain instances of 
<i ciecasominemasasisibae tel GE 
' Sometimes their sink é been i i i vif 
' use of their own weight but becs 
jogreg ot the supporting plants are eaten by insec < . 
Bee Aleock in Ann Mug. Nat. Hist, (6) X, 1892, p. 208. 
