CHAP DH RL 
Eth MIGROS? OBIE AL, WA UNA 
OF THE 
CRETACEOUS IN MINNESOTA, WITH ADDITIONS 
FROM NEBRASKA AND ILLINOIS 
(FORAMINIFERA, RADIOLARIA, COCCOLITHS, RHABDOLITHS). 
BY ANTHONY WOODWARD AND BENJAMIN W. THOMAS. 
I. METHODS OF MICROSCOPIC PREPARATION. 
The microscope of a few years ago, if compared with that now in use, was 
of bat little practical value, and was regarded more as an amusing toy than as an 
instrument of absolute necessity in scientific investigation. The geologist and the 
botanist were apparently satisfied with their pocket lenses, and the physician had 
but little use for even these. Careful students, however, were getting occasional 
glimpses of fields just beyond their power of satisfactory resolution. These a some- 
what more powerful combination of lenses would, to some extent, resolve, but would 
at the same time show that there were much larger and more interesting ones yet 
beyond their reach. Scientists and physicians at once called for objectives of higher 
powers, and for improved appliances, and manufacturing opticians of Europe and 
America have promptly and satisfactorily responded to the demand. Excellent 
instruments can now be secured at prices within the reach of every student. 
Geologists have long been familiar with fossil remains of pre-historic life, so 
abundant in most of the geological formations, but it is of comparatively recent date 
that improved microscopes have shown them that of these vast deposits there is 
hardly a cubie inch that does not contain the wreckage of an earlier world that 
teemed with animal and vegetable life, and from which can now be studied its 
history, climate, etc. These revelations are not infrequently of great commercial 
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