Miscellaneous. 487 
of its period of summer growth would be a less cause of pollution to 
the water-supply than that of any other sponge. 
Moreover, from recent investigations into the life-history of these 
low organisms, he was inclined to believe that decay was not the 
normal or necessary result of the close of each season’s growth. 
The fragile branches of some species inhabiting exposed situations 
may, of course, be broken off and destroyed while the sarcode still 
covers them ; but in the sessile portions, and in all when sufficiently 
protected, the cells of the sarcode at the period of full maturity, for- 
saking their places along the lines of the skeleton framework, gather 
together by simultaneous amceboid movements into dense groups, 
where they are soon covered by a tough chitinous “ coat,” which, in 
time, generally becomes surrounded by a “ crust ” of minute granular 
cells, and armour-plated by a series of protective spicules. These 
groups are now recognized as the statoblasts, gemmules, or winter- 
eggs of the sponge—eggs only in appearance—in reality the resting- 
spores or protected germs which conserve the life of the individual 
through the cold and storms of winter, and awake very early in the 
springtime into new life—yet a continuance only of the same exis- 
tence which was seen a few months before nestling into this winter’s 
sleep. 
If this is the ordinary course with these organisms there seems 
no reason to regard them as serious causes of the pollution of our 
streams, though violent freshets before this resting-period is reached 
may tear them to pieces, and their decay may give a temporary 
taint to the water. 
Continuing the narrative of his exploration, Mr. Potts described 
the iron pipes which had lain for many years upon the bottom of the 
forebay, as covered, in some places to the depth of an inch or more, 
with a crust richly coloured by iron oxide, but principally composed, 
as were the others, of the spicules and statoblasts of MZ. Leidyi. 
Upon the surface of this crust in places he found the remains of 
large colonies of Urnatella gracilis, Leidy. In the absence of any 
positive knowledge of the winter condition of this curious polyzoan, 
Mr. Potts had examined with much interest a novel form of statoblast, 
which was frequent upon the same pieces of sponge; but he was 
unsuccessful in associating it with the polyzoan. It is most pro- 
bable that the life is continued, as suggested by Dr. Leidy, within 
the urn-like joints of this creature, and that they put out buds and 
anew growthinthe spring. To discover if this were the case, he had 
placed some fragments in water, and while awaiting results he had 
been surprised at the appearance within a few days amongst the 
fragments of Urnatella of numbers of the recently described cheeto- 
branch worm, Manayunkia speciosa of Leidy, as well as several 
living cells of a species of Paludicella, probably P. elongata, of the 
sameauthor. ‘The persistence and tenacity of life in these apparently 
delicate creatures, overcoming not only the severity of a hard winter, 
but an exposure of several days in the open air, were further com- 
mented upon.—Proc. Acad. Nat. Sci. Philad., Feb. 12, 1884, p. 28. 
