254 PROGRESS OF MICROSCOPICAL SCIENCE. 
class of fungi it assumed different forms under different cireum- 
stances. It might be that the fly got into a diseased state, and 
settled upon the moist window pane—for it was only to be observed 
in damp weather. In the fifth volume of the ‘Quarterly Journal of 
Microscopical Science,’ p. 154, some account of it would be found ; 
and in vol. iii. p. 55, of the early Transactions of the Microscopical 
Society, it was described and figured by Mr. Cornelius Varley. Mr. 
Reeves added that the fungus was not confined to the house-fly—it 
was found also on the blow-fly and several other insects. 
Early Development of Sponges.—In a recent report of a meeting of 
the Société Vaudoise des Sciences Naturelles, ‘ Nature’ says that Pro- 
fessor Forel spoke on an interesting occurrence of an early develop- 
ment of sponges in the Lake of Geneva, due to the unusually mild 
winter of this year. The fluviatile sponge of the lake consists of 
a horny skeleton with very fine siliceous spiculs, covered with a 
sheet of soft, perforated animal matter. Usually, in autumn, this 
soft matter leaves the exterior ramifications and condenses under the 
form of small gemmule, half a millimeter in diameter, in the deepest 
interior parts of the horny skeleton. There it remains until the 
spring, when it expands anew upon the ramifications, and covers them 
with a sheet of living animal matter. But this year M. Forel observed 
on February 2, besides many sponges in their hibernal state, a colony 
of other sponges which had already reached their full summer de- 
velopment, differing only by a somewhat paler colour from the usual 
summer appearance. The occurrence is perfectly explained by the 
circumstance that the temperature of water in the Lake of Geneva was 
this year higher by two degrees than the average temperature for 
many years, which is 6°°3 Cels. for December and 4°°9 for January. 
The Structure of Itacolumite has been recently described to the 
Academy of Natural Sciences of Philadelphia,* by Professor W. P. 
Blake. The specimens, which were obtained in California, were un- 
usually fine, some being over 30 inches in length, and only 2 square 
inches in section. The colour and the structure appear to be the 
same as in flexible sandstone from other localities.. Thin and 
small scales of silver mica are abundant. It bends with little re- 
sistance up to a certain point, and without elasticity, but is rigid 
beyond that point. When held up by one end and shaken, the motion 
is transmitted in wave-like vibrations as in a cord, but the limit of 
movement is sensibly felt like a blow or shock. A specimen 32 
inches in length may be bent 73 inches to one side or the other of 
a straight line. The freedom of movement is greatest at right angles 
to the plane of lamination. The specimens are also capable of being 
sensibly extended when pulled. In a specimen 82 inches long the 
extension amounted to about half an inch. The freedom of movement 
up to a certain point and the rigidity beyond that point indicate that 
there is a tolerably uniform distance between the grains of sand and a 
certain amount of movement possible among them, and that by bend- 
ing, the grains are brought into contact with each other. The theory 
* December 3, 1876, 
