336 Dr Grant’s Observations on the Structure 
monia, the flint-glass bottles in which it has been for some time 
kept are invariably rendered much more brittle, and pieces 
of glass fall out upon very slight motion of its contents. This 
fact is merely men tioned as curious* and may probably be here- 
after more fully examined. 
Art. XIX . — Observations and Experiments on the Structure 
and Functions of the Sponge. By Robert E. Grant, 
M. D., F. It. S. E., F. L. S., M. W. S., &c. (Continued from 
VoL XIII. p. 124.) 
though a minute examination of the internal structure of 
the living sponge is obviously the most natural and necessary 
step towards discovering its mode of growth and generation, and 
consequently the place this substance occupies in the scale of 
beings, and is certainly that most likely to lead to the discovery 
of some more fixed and scientific principles for discriminating 
the species, than the vague characters hitherto employed ; yet 
we can scarcely discover, in the writings of zoologists, since the 
time of Aristotle, any attempt to investigate its structure in a 
scientific manner. Although Pallas, Lamouroux, Lamarck, 
Schweigger, and almost every modern zoologist, have considered 
the examination of this animal, in its recent state, as still an im- 
portant desideratum in comparative anatomy ; yet the deficiency 
is generally supplied only by ingenious conjectures from the ap- 
pearance of dried specimens, or by supposed analogies with other 
vegetable or animal productions, rather than by patient dissec- 
tion of the animal in its natural state. Cuvier states in his 
Regne Animal (t. iv. p. 87.), that the sponge is a fleshy sub- 
stance, possessing no axis, either calcareous or horny ; although 
we shall find, that, in one great tribe of these zoophytes, with 
spicula of complex forms, the axis is entirely calcareous and so- 
luble, with effervescence, in acids ; and it is well known, that 
the horny axis, of several sponges, have been constantly em- 
ployed in the arts since the time of Alexander the Great, if not 
since the period of the Trojan war. Professor Schweigger of 
Konigsberg, who examined these animals alive, principally at 
Nice, believes that their axis consists of fibres which possess a 
