98 THE MICROSCOPICAL NEWS. 
FRESH WATER SPONGES IN THE FOREBAY 
AT FAIRMOUNT. 
HE inlet by which the sweet waters of the placid Schuylkill are 
conveyed to the turbines of Fairmount is undergoing renovation. 
A peep into its muddy depths shows the walls to be covered with a 
brownish layer, while a double line of broken iron pipes is coated 
with what appears to be rust. This glimpse is enough for ordinary 
mortals, but did not satisfy the mind of Mr. Edward Potts, our 
Philadelphia spongiologist. With the binocular intention of find- 
ing out something new about sponges, and of ascertaining whether 
his humble pets were responsible for any considerable proportion 
of the impurities in our drinking water, Mr. Potts descended into 
this Avernus. The results obtained, omitting the details of the 
trip, were given at the meeting of the Academy of Natural Sciences 
on Tuesday last. 
Nine-tenths of the incrustation, which covers the walls to a thick- 
ness of three-eighths to one-half an inch, consists of the spicules, or 
solid needles of silica, and of the statoblasts, or winter nests of a 
small sponge known as Meyenia Letdyiz. With this is a much 
smaller quantity of the larger and somewhat branching Spongilla 
Sragilis. The material upon the iron pipes is also a layer of the 
former sponge. ‘The speaker not only denied that sponges added 
much to the impurities of the water, but stated his belief that those 
living in fresh water did not, under ordinary conditions, de at al/. 
This may seem a wild idea to those who think that all living things 
must ultimately turn to dead bodies; but the fact is, that it is well- 
known that all those forms of life which consist of a single cell 
(protozoa) do not die, as higher animals die. They increase by 
division, then divide again, and so on, till ultimately they become 
quiescent, surround themselves with a horny pellicle, and thus rest 
awhile. When the proper conditions surround the little cyst or sac, 
the covering bursts, and hundreds of tiny spores flow out, each of 
which, after growing awhile, divides and subdivides like its pre- 
decessors. Thus the protozoa leave no dead bodies. The sponges 
are essentially large aggregations of one-celled animals, living upon 
a more or less thoroughly woven skeleton, formed of needles of 
flint (silica) or lime, most commonly the former. It has long been 
known that in winter the sponges which live in fresh water form 
winter eggs, or rather winter nests (statoblasts), and it has been 
usually thought that the greater part of their soft animal substance, 
or sarcode, slipped off into the water and there decomposed. This 
Mr. Potts believes not to be the case. He believes that the living 
cells are all drawn together and concentrated in the statoblasts, just 
as protozoan in itscyst. He has seen the living particles of the crea- 
Sinaia 
