Dr Grant on the Structure and 
In its living state, the Sp. friabilis is so soft and brittle that' 
it can scarcely be handled or lifted without tearing, feels slightly 
unctuous between the fingers, has a strong disagreeable smell, 
like that of stagnant ditches in the heat of summer, tastes cool- 
ing without any marked flavour, and quickly diffuses among 
the saliva, leaving only some earthy particle between the teeth ; 
it sinks slowly in water, appearing lighter than most marine 
sponges. When pressed, a thin slimy turbid greenish-coloured 
matter escapes, mixed with a considerable portion of water, and 
the remaining fibrous portion has a light grey colour, and stiff 
gritty feel. When allowed to putrefy in water, a thick, fatty 
layer covers the surface of the fluid, the water acquires a tur- 
bid yellowish colour, the spongilla becomes of a blackish-green 
hue, and emits a most offensive putrid animal odour, like that 
of the most putrid offals. A portion of it, whether fresh or 
putrid, placed on a red hot iron, smells like burning skin or 
membrane, the soft parts are dissipated, and the fibrous residue 
becomes red hot, but does not consume nor change much its 
form. The burnt remains of this substance do not effervesce in 
vinegar, nor in nitric,, sulphuric,, or muriatic acids, nor is their 
appearance in the least altered by these acids, although they 
are alleged by Lamouroux to contain more than half their bulk 
of lime. When the calcined remains, or even a portion of the 
fresh spongilla, are rubbed with a smooth, wooden, instrument on 
the polished surface of glass, they leave innumerable very mi- 
nute permanent traces, which we observe, with the assistance 
of a lens, to be distinct streaks cut in the substance of the glass, 
thus indicating the presence of silica in the axis of this organized 
body. The soft green coloured matter contained so abundantly 
in this substance, in its living state, when mixed with water, and 
examined under the microscope, is found to consist almost en- 
tirely of minute, granular, transparent bodies, like the gelatinous 
matter of the marine sponge. The dried fibrous axis becomes 
of a pure white colour, and somewhat opaque, by a few minutes*’ 
exposure to the intense heat of the blowpipe, but does not melt 
nor lose its fibrous appearance ; when a portion of the dried 
axis is rubbed on the back of the hand, it excites an itching 
pain, and inflamed spots with diffused redness, from its sharp 
spicula piercing the skin, and remaining in its substance. Nu- 
