PHYSIOLOGY. 
Sjpong. 5 
subdermal cavities of Sponges have a gastric function. Carmine par- 
ticles are absorbed by all free surfaces, both ectodermal and endo- 
dermal layers, but are subsequently cast out into the surrounding 
medium, except by the cells forming the floor of the subdermal 
cavities ; these pass them on to the adjacent wandering amoeboid cells, 
by which they are absorbed, and subsequently, by the migration of 
these cells, carried to the flagellated chambers, to the collared cells of 
which they are transferred, and by them expelled into the excurrent 
canals, as effete residues. The author also investigates the functions of 
tho glandular colls doscribod by him. Wliou irritated by the presence of 
fresh-water, they become remarkably active, pouring forth in large quan- 
tities a slimy secretion, the chief constituent of which is supposed to be 
spongiolin. A specimen of Dendrilla rosea, which weighed in the fresh 
state 77 grammes (the water of the oscular tube having been in greater 
part removed), was washed with distilled water and placed under a bell- 
jar; in fourteen hours its weight was reduced to 51 grammes, and 
24.5 grammes of secreted matter had been poured out. The glandular 
cells and the epithelium of the exterior disappear as the secretion pro- 
ceeds. The pigment granules of the amoeboid and flagellated cells of 
the mesoderm are regarded as having a function somewhat similar to that 
of the red blood corpuscles of the higher animals. 
Carter (4) describes the presence of starch granules and oil globules 
in the ova of several marine Sponges. 
Nassonow (16) has watched the progress, in its various stages, of 
(7/mna-embryos as they eat their way into a transparent lamella of car- 
bonate of lime. He shows that the spicules take no part in the process 
of excavation. 
Thoulet (25) gives the results of experiments on siliceous spicules 
derived apparently from an Hexactinellid Sponge. Heated to redness, 
they decrepitate violently, and turn white and opaque, without, however, 
losing their form. The loss in weight after calcination is 13.18 per cent. 
The specific gravity of the spicules was found to be 2.0361 at 16° 5 C. 
The substance of the spicules agrees, in all the characters displayed, with 
opal. 
Marshall (14) argues, from the structure of the statoblast of Spongilla 
nitens (Carter), that it is adapted to transportation by winds ; the stato- 
blasts of Parmula brownii , a South American species, are firmly united to 
the Sponge skeleton, and hence are secured from detachment when in the 
dry state ; the statoblasts of S. jluviatilis are heavier than those of S. 
lacustris , and this saves them from being washed too far away by the 
river current ; the three layers of amphidiscs in the statoblast of 
Myenia mirabilis similarly serve to weight the statoblasts, and probably 
stand in relation to the rapidity of the river in which this Sponge 
occurs. 
Yejdovsky (28) considers that the air-chambers of the statoblasts of 
Trochospongilla erinaceus have an aerostatic function ; they are analogous 
to the natatory rings of the statoblasts of fresh-water Polyzoa. 
Rathbun (21) describes first successful attempt at Sponge-cultivation 
in America. Four specimens, all of the finest or sheep’s wool variety, were 
