biology. 
Spong. 11 
Letellier (43) again treats of the manner in which the boring 
Sponges excavate their burrows. He says that if a small object is firmly 
attached to an oyster-shell and then torn off, it takes a portion of the 
shell with it and leaves a cavity, similar to the microscopic cavities in the 
walls of the tunnels excavated by the Vioa. The traction necessary to 
tear out a piece of the shell in this manner is smaller than the traction 
necessary to tear the tissue of boring Sponges. According to L., the 
boring Sponge produces some adhesive substance, glues itself therewith 
at any given point to the oyster-shell, then contracts in such a manner as 
to exert strong traction on the bit of shell-surface to which it is glued, 
tears a semi-globular piece out of it and finally ejects this. [The 
Recorder has observed a strong cuticula on all the surfaces of the boring 
Vioas coming in contact with the stone or shell in which they live.] 
Hundeshagen (29) gives an account of the iodine contained in the 
horny Sponges. This he says was the effective part of the “ Spongim 
ustae ” of the old Pharmacopoea against goitre, and was first proved to 
exist in Sponges analytically by Vogel, jun. The bath Sponge contains 
only very little iodine, some tropical forms, however, which H. examined, 
were found to contain 8-14 per cent. : Aplysina cauliformis ( Luff aria 
cauliformis, Carter), 8-10 per cent. ; Aplysilla compressa ( Aplysina com- 
pre-ssa , Carter), 9-10 percent. ; and a Sponge [unknown to the Recorder] 
named Verongia plicifera , 11-14 per ceut. No doubt all these analyses 
refer to the skeleton only. The “ eingetrocknete Fleischmasse ” of the 
last named contains 10 per cent, of iodine. In all these 1-2 per cent, of 
bromine and chlorine were also found. The loss macoratod and darker 
specimens contained much more iodine than the more macerated lighter 
coloured ones. Also in other tropical species, which the author refers 
to Stelospongos , Ccicospongia, Luff aria, and Verongia , iodine was found, 
sometimes in great quantities, whilst in the tropical species of E uspongia, 
Euchalina, and Clialinopsis , only very little iodine, no more than in the 
common bath Sponge, was met with. The Mediterranean Aplysina 
aerophoba contains but little iodine, although its tropical relations are 
so rich in this substance. Bromine and chlorine, however, occur also in 
this species in considerable quantities. 
That tropical Sponges, as a rule, contain more iodine than those of 
cooler climes, is analogous to the fact that the seaweeds of the tropics 
(the Gulf-stream drift-ww d of the west coast of Ireland) is three times 
as rich in iodine as the seaweed of the temperate zone (the CMi-weed of 
the Irish coast). 
The chemical composition of the Spongin seems to be the same in all 
the Sponges rich in iodine, which the author calls iodine Sponges. It 
contains about 11-12 per cent, nitrogen and 4-6 per cent, ash (mostly 
carbonate of lime). On heating it burns under the formation of violet 
vapours. Boiling water has little effect. Under high pressure, however, 
the super-heated water dissolves the Spongin, whereby the iodine com- 
pounds are destroyed aud the iodine itself left in the shape of iodide of 
ammonia. Ether, alcohol, etc., dissolve hardly any part of the Spongin. 
