of one-tenth of an inch focal length. They are oblong or cylindrical 
membranous cells, pointed at each end. Their axis is dark coloured, 
and composed of a bundle of extremely fine spiculz, lying parallel to 
each other, and each of them is nearly as long as the cell. Upon 
watching these objects for a little while after they have been placed 
in water under the microscope, the spicule are seen to be ejected one 
by one, at ihe one or other, or both extremities of the cell. The reaction 
caused by their ejection moves the cell a little to one side, so that the- 
spicule are not all discharged in the same direction, and in conse- 
quence they ultimately lie in a confused heap near the point of exit. 
These organs are so very singular in their structure, and the phenome- 
non they present is so remarkable, that we are tempted to extend our 
notice of them, by condensing the detailed account of M. Turpin, in the 
sixth volume of the new series of the Ann. des Sciences They are there 
described as always lying between the vesicles of the cellular tissue 
which they exceed in size, being about j; of a millimetre (?) in length. 
They are composed of three separate parts. The first consists of an 
exterior perfectly transparent and colourless, though rather thick mem- 
brane, forming a vesicle, which is either fusiform, or a cylinder termi- 
nated by cones, and which, consequently, when seen under the micro- 
scope in profile, appears either like an oval, or a hexagon, with two of 
its opposite sides considerably elongated. Each extremity is perfora- 
ted by a small opening, with the edges a little thickened. The second 
part consists of an inner fusiform vesicle, composed of a transparent, 
and extremely thin membrane and lying in the axis of the outer ves- 
icle, and extending its whole length, but with the transverse diameter 
not occupying more than one third of that of the outer vesicle. Within 
this inner or intestinal vesicle, lies the bundle of numerous acicular 
chrystals, of nearly the same length as the two vesicles, and completely 
filling the inner one. A single spicula appears to be perfectly colour- 
less, but collectively they assume a yellowish or brownish tinge. The 
biforines are therefore composed of two organized coats, and these in- 
organic chrystals. In order that the spicule may be ejected, the bifo- 
rines must be immersed in water whose temperature is not less than 20° 
C. and then they are emitted at short intervals, from 1 to 6 at a time, 
the biforines recoiling at each discharge like a little cannon. When all 
the spicule are emitted, the intestinal vesicle collapses; and ultimately 
the exterior one also does the same, to a greater or less extent. To 
explain this action, Monsieur Turpin supposes that the space between 
