Tae MicroscoricaL Nrws 
AND 
NORTHERN MICROSCOPIST. 
¢ 
No. 48. DECEMBER. 1884. 
Powe, OF POLARIZED LIGHT VEN 
VEGE TABLE) HISTOLOGY. 
Translated from the German of Professor Dr. L. Dippel. Zeitschrift fiir wissen- 
schaftliche Mikroskopie, 1884. 
By W. BLackBurRn, F.R.M.S. 
\BSERVATION with polarized light in vegetable histology has 
hitherto not found very extensive employment, except in a 
few instances, although it is of much importance to the decision 
of many questions. The reason of this may depend partly upon 
the fact that it is still by no means certain how the phenomena 
arise, which present themselves by this method of observation in 
the vegetable cell, especially in the cell-wall, as well as in certain 
parts of the contents ; whether they arise through molecular change 
in the building-up of the organic substance or through tension- 
relations. On the other hand, the reason may be that certain re- 
lations of structure, &c., (which observation by polarized light is 
able to explain) may also be ascertained by other methods, as, for 
instance, by chemical re-actions, colouring, &c. One reason may 
also be the fact that if one would aim at results which admit 
of no doubt, this method of observation requires the most success- 
ful preparations in all cases where fine structure-relations are 
concerned, whilst in incompetent preparations there is little or 
nothing to be seen. Whereas, upon the one hand, observation 
with polarized light affords abundant proof of results gained by 
other methods, and, upon the other hand, may be able to throw 
light upon facts previously observed, which otherwise would not 
be so completely confirmed as by its means, therefore this means 
should nowhere escape notice, when the conditions of the case 
point to its application. 
These lines should serve to direct deserved attention to a method 
of observation which has afforded me much assistance in my re- 
searches into the finer structure of the cell-wall ; and I will here briefly 
VOL. IV. 
