1917] FAUST—RESIN SECRETION 447 
used to determine the character of the Casparian strip. Slow alco- 
holic penetration into inulin-testing areas caused a precipitate of 
this polysaccharide in the shape of sphero-crystals and rhombo- 
spheres, while a more rapid penetration caused the material to be 
precipitated in granular and amorphous masses. Resene was 
tested for im situ by the Mach and Salkowsky-Hesse cholesterol 
methods (somewhat modified to suit the immediate needs). Crys- 
tals of resene found in certain cells were positive to these tests. 
Similar crystals were found as a check in steam-distilled resene, 
dissolved in alcohol, and allowed to crystallize as the alcohol evapo- 
rated. A more complete discussion of these tests will be found 
under tests for resene. 
The probability of error in resin tests is due in general not to a 
lack of a specific reagent, but to errors in location of the substance. 
Due to its solubility in high grades of alcohol it is not impossible 
that it might become translocated by alcoholic diffusion. Due to 
its viscous nature it might readily be dislocated in cutting sections 
from fresh or alcoholic material. The data of certain investigators, 
among whom are MUELLER (15) and VAN TIEGHEM (22), show no 
resin in the resin canals, while Santo (18) and TscHtrcH (21) were 
unable to find the secretion outside of the canals. Errors in tech- 
nique must have been responsible for this. TscurrcH considered 
ordinary methods of technique inadequate for the elimination of 
the error and made use of a method adapted from MUELLER (loc. 
cit. p. 390). He dried the material at 100° C. for some time before 
cutting. He then stained with alkannin tincture in water (2 parts 
of the tincture and 5 parts of water). The former procedure 
allowed all volatile oils to be driven off and hardened the resin to 
a tough gummy consistency, so that it was not easily removed from 
its original position by the section cutter. The latter diluted the 
tincture so that the resin would not readily dissolve in the alcohol. 
By this method Tscutrcu was able to demonstrate resin in the 
form of a dense slime in the canals of Imperatoria Ostruthium, 
Arnica montana, and in the leaves of Abies pectinata and A. Nor- 
manni; while the surrounding tissue, especially the secretory cells, 
was free from resin content. The writer has given due weight to 
this possible source of error, and has made many preparations from 
