The Midland Naturalist 
PUBLISHED Bi-MONTHLY FROM THE BIOLOGICAL 
LABORATORIES OF THE UNIVERSITY OF NOTRE DAME 
Vol, I. JUNE, 1909. No. 2.* 
Fresh Water Sponges and Particularly Those of the 
United States. 
. A. M. KirscH. 
In the beginner's class of Zoology there is invariably noticed a 
doubting expression of surprise when it is announced that the next 
subject to study is the Fresh Water Sponge. I fancy I can see the 
same expression on the face of those of my readers who may doubt 
that sponges are found in the nearby brook, river or lake. P 
be sure, such sponges as the average man knows about, and which 
he can buy in the nearby drug store, are notto be looked for in our 
ponds and ditches; they must be sought in the far away 
Mediterranean Sea or down on the coasts of the Bahamas or on the 
Keys south of Florida. 
There are many kinds of sponges — just as there are 
many kinds of roses or violets. This comparison reminds 
me also of the necessity of stating that sponges are not vegetable 
growths, as was once believed even by all the scientists and is still 
believed by many otherwise well educated people. It was in the 
middle of the 19th Century that it became definitely settled that 
sponges belong to the animal kingdom. They are now very often 
placed by themselves into a proper phylum called Porifera though 
some had placed them formerly with the Protozoa as compound 
Choanoflagellata, and many at present associate them with the 
phylum Coelenterata. Very little attention is to be paid at present 
to the various systems of classifications in vogue. They are all 
transient and provisional, and this is the most annoying con- 
dition of Zoology to the beginner. He takes up one text-book 
after another and he finds in each a different system of classifica- 
tion ; and it is wise in the part of the teacher to show him from the 
beginning, that classification of animalsisnot after all the important 
* June 15, 1909.—Pages 29 to 60. 
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