* 
3a MIDLAND NATURALIST. 
focus and one cannot go wrong. Of course, the first question 
naturally is: ‘‘Where shall I look for them, and how can I tell 
when I have found a Fresh Water Sponge?’ 
One will soon find that many of the troubles are imaginary 
ones, as to my own surprise I found them more readily than I had 
expected, and having found them, I knew they were what I was 
looking for in spite of the difficulties I had anticipated. 
It was in the middle of September many years ago that I set 
out for the banks of theSt. Joseph River in Northern Indiana. The 
banks were steep and some old stumps of trees were scattered along 
the shore, with their twisted roots reaching out in all directions. I 
soon noticed in the swift current that on some of the roots were 
greenish looking tufts—I secured a few of them, and hardly had I 
touched them, when I knew I had found what I had been looking 
for. The sponge mass is not the same as Cladophora. One will 
know it at once and will never forget it. Under the hand lens one 
will see the little needle-like spicules sticking out in all directions, 
but more than this in the interior of the mass one notices the small 
round globules, so characteristic of the Fresh Water Sponges. These 
globules are the gemmules and whenever these small globules are 
found in a greenish mass one may be sure that the specimen is a 
sponge. It is needlessto look for sponges in the springtime, but one 
will never fail to find them later in the year and especially in 
August and September. 
hese gemmules are bodies peculiar to Fresh Water Sponges, 
and have never been found in salt water forms. They are known 
in the literature of sponges as: Ovaria, gemmules, statoblasts, 
statospheres, sphaerules, etc., but at present the term ‘‘gemmules’’ 
is mostly used. I stated above that one must look for greenish 
masses, but this must not be taken to mean that the color is always 
. green; the fact is they are often brown, gray and white ac- 
cording as they are more or less exposed to the light. Though a 
few have been found in muddy localities, they must, however, as a 
rule be sought in clear, pure and rapidly running water. A 
- favorite locality is in shallow water of rivers, and they grow on 
loose stones, but one seldom fails to find them on rocks, timber, or 
“loose boards at the end of a mill race or fall, or on the lining board 
and casings of sluice-ways. They should never be looked for in 
< . shallow waters that have a muddy bottom. 
` Sometimes they may be found on plants growing in lakes and 
-< they will spread over these plants like a thick cobweb or cushion. 
5 A long pole with a scraper attached to the end in connection with 
