Opaque Objects with Sigh Powers. By G. JV. Moorehouse. 29 
microscopical work. If he knows not by previous study of the fresb 
tissues, what nature puts in them, he will not be successful in 
revealing them best in mounted preparations. 
Biological science is not to be studied from microscopical slides, 
no more than from stuffed animals or dead shells in our museums. 
Botanists do not get best education by poring over mounted spe- 
cimens, however beautiful they may be, no more than they do by 
daily browsing on the desiccated vegetation in herbaria or hay- 
stacks. We must go to the living for the best use of our instru- 
ments, and a knowledge thus obtained of structural detail is essen- 
tial before any attempt should be made to preserve such details in 
mounted preparations. Some post-centennial work in botany, aim- 
ing at that result, has been exhibited before the Section, in which 
every cell showed the cell anatomy ; the nucleolus, nucleus, proto- 
plasmic contents, and cell- wall were all apparent at one view. De- 
monstration which falls short of this is unsatisfactory, because 
important morphological details are not brought out, and such 
work, like fossils in the rocks, belongs to a past era in microscopical 
technology. — The Cincinnati Medical News, March. 
VI. — Opaque Objects with High Powers. By Gf. W. Moorehouse. 
A few words, giving experience in the use of opaque illumination 
with the highest powers of the microscope, may not prove entirely 
without interest. Some of the powers now successfully used in 
this way have even been thought extraordinary when used with 
transmitted light, and this may have led some persons to doubt the 
practicability of this method, and so prevented their giving it a trial. 
There are no natural tests yet known to have been well defined 
by the best microscopes that may not be seen with a power of 500 
diameters. Of course it is often necessary, in order to understand 
the structure — say to distinguish circular markings from hex- 
agonal — to resort to an amplification of 2000 to 4000. Can such 
powers be profitably used with illumination from above the object ? 
Many errors of interpretation arising from the use of trans- 
mitted light might be avoided if we could view all microscopic 
objects by light reflected from them, as we do almost everything 
we see with the naked eye. Yet with careful and practised use 
of transmitted light the same results may be obtained on suitable 
objects. 
Place a thin leaf of honeycomb between your eye and a lamp, 
and mark the varying appearances and shadows as you increase 
the distance between the object and the eye, and as the position 
of the lamp is changed from central to oblique. Something of an 
