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Transactions of the Wisconsin Academy of Sciences, Arts and Letters
volume XXIII (1927)

Harring, H. K.; Myers, F. J.
The rotifer fauna of Wisconsin. IV. The Dicranophorinae,   pp. [667]-Plate 49 ff. PDF (41.5 MB)


Page 673


Letters.
s then with
nce became
l to compare
(gton and in
rences were
o how to ac-
be found on
e important
Toidable; no
e to prevent
zrences were
stances pres-
re was very
   We knew
Washington
coastal Plain
!olumbia, ac-
ashington, is
teau and the
olidated cre-
transported
r e generally
able amounts
. The New
ition of the
nd; the sur-
its extremely
tV water is
m carbonate,
rmination of
-bon dioxide.
mned doubtful
The differ-
could always
igin at once.
; entirely too
ices between
rotifers that
Ith the varia-
,    I
   I
  Harring & Myers-Rotifer Fatna, of Wi.scov'sin.-IV. 673
  The opportunity to study the rotifers of the state of Wis-
consin offered a welcome opportunity to check what had
already been learned. Geological conditions here are sub-
stantially parallel to both Washington and Atlantic City;
the southern part of the state is covered with Silurian and
Ordovician limestones and dolomites, and the surface waters
are hard. In the northern counties the last stage of glaci-
ation removed all soils down to the Archean and Protero-
zoic bed rock which the retreating glaciers eventually buried
under 200-800 feet of till, derived from the siliceous Arch-
ean rocks in adjacent portions of Canada; the water in the
numerous lakes and ponds is everywhere soft. The re-
sults of the rotifer collections agreed generally with what
had been observed at Washington and in New Jersey; it
was evident that rotifer distribution could not be correlated
with dissolved calcium carbonate or total available carbon
dioxide.
  About this time our attention was called to the work of
Coville and Wherry on soil acidity and plant distribution.
This seemed to offer a promising line of attack. Hydro-
gen ion concentration was being demonstrated as very im-
portant in physiological processes and, if it plays a part in
plant distribution, the same effect might hold good for roti-
fers. That this is really the case has been abundantly
proved since systematic measurements of hydrogen ion con-
centration have been made, and we believe that we are jus-
tified in stating that rotifer distribution is directly depend-
ent on it. Neutrality, or pH 7.0, seems to be the dividing
line; above this, in alkaline waters, are found all the "cos-
mopolitan" rotifers, enormous numbers, but relatively few
species. A  complete change occurs when the reaction
drops below pH 7.0; the number of individuals is much
smaller, but there seems to be no end to the number of spe-
cies. This continues until the acidity becomes very pro-
nounced, and at pH 4.0 but very few species of' rotifers re-
main. Some numerical comparisons of acid and alkaline
waters may be of interest. During three months collec-
tions were made daily in alkaline waters of southern Cali-
fornia, and 106 species were found; a single trip to Lenape
Lake, near Atlantic City, made for the purpose of checking,
netted 84 species. Exactly 100 species were collected in
43
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