84 
On Methods of 
rMonthly Microscopical 
I Journal, Aug. 1, 1869. 
surface of an equilateral prism, but far too much to allow it to take 
the place of the prism which alone supplies a beam of pure un- 
polarized hght at the angle of total reflexion. 
V. — On Methods of Microscopical Research. 
By Here S. Stricker * 
The microscope is an implement of research. When objects are too 
small to give, at the necessary distance from the eye, a sufficiently 
large image on the retina, they require a simple or compound 
microscope for their investigation. But the field over which the 
investigation ranges is not determined by the employment of such 
an instrument. Microscopy denotes not a doctrince but a method 
of investigation, the most dehcate indeed of its kind for terrestrial 
objects, for our microscopes now are the most perfect of optical 
instruments. 
The most extensive use has hitherto been made of the micro- 
scope in the investigation of organisms. The knowledge of the 
more minute structure of the tissues of the vegetable and animal 
body, and especially of the latter, has been raised to an independent 
science, which branches again into important subdivisions. Normal 
tissues, and those altered or produced by abnormal influences, form 
already the basis of two distinct — though very intimately connected 
— sciences, and either may again be considered from two points of 
view. We occupy ourselves with the morphology or the biology 
of tissues, or, as it may be also expressed, the normal or patholo- 
gical anatomy, or the normal or pathological physiology of tissues. 
Morphology and physiology of tissues are, however, so intimately 
related to each other, that we cannot now think of a separation of 
the two. The observation of the vital phenomena of tissues, and 
experiments with them, will lead us to a large knowledge of their 
most intimate structure, whilst, vice versa, a research into their 
structure will facihtate our conclusions in regard to certain vital 
phenomena. 
The methods which have been applied in these two departments 
are difierent. To watch the vital processes under the microscope, 
and then to influence them, require other means than those which are 
necessary for acquiring a knowledge of only the forms of the elements 
of the tissues. Besides, experiments under the microscope upon 
living objects are of a difierent nature from those upon dead ones. 
The sensitiveness of the former to external influences renders, in even 
* Translated from the ' Handbuch der Lehre von den Geweben,' Leipzig : 
Engelmann, 1868. 
