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122 MEASUREMENT.
Unit of Measurement.
I have adopted in this work a hundredth part of a millimetre
(o'oimm.), as the unit of measurement. I believe it to be the only
convenient measure for organisms, whose size is so variable, that their
maximum is often double their minimum size, and of which a con-
siderable number are so large that if the mikron is used, too high a
number (generally reaching into hundreds) has to be quoted.
We mark this unit by three letters, c.d.m. (centiemes de millimetre).
One c.d.m. = '0003937 English inch= io/j. (mikrons).
End of Introduction.