— 86 - 
which vary from .007 
to .012 millimeters in 
length and from .005 
to .007 in breadth we 
should write the ex- 
pressions ^ mic. or//. 
As soon as possi- 
ble after an unknown 
specimen is collected 
it is desirable to ex- 
amine the spores. 
Having made a thin 
section of the apothe- 
cium or removed a 
small portion of the 
hymenium, it may be 
treated with a little 
potassic hydrate on 
the slide and crushed 
somewhat under the 
cover glass. Iodine 
is sometimes useful 
as a coloring agent. 
It gives a yellowish or 
brownish tinge to pro- 
toplasm and turns the 
thekes blue. The 
microscope should be 
provided with an eye- 
piece micrometer and 
the value of the divisions should be carefully ascertained for each objective. 
Thus equipped it is an easy matter to measure the spores, and these measure- 
ments should be recorded on the label of the specimen together with a draw- 
ing of a spore, showing outline, number of septse and (by shading) the 
presence of color. Cambridge, Mass. 
(To be continued.) 
f. 17. Forms of spores. A, globose; B, ellipsoid; C, ovoid; 
D, oblong; E, dactyloid; F, oblong-ellipsoid; [G, cymbi- 
form; H, fusiform; I, acicular; J, cylindrical. A and C 
are simple; D, bilocular; E and I, quadrilocular; H. and J, 
plurilocular; B, polar-bilocular, F and G, muriform. (Ori- 
ginal. ) 
WHAT TO NOTE IN THE MACROSCOPIC STUDY OF LICHENS II. 
Bruce Fink. 
Variation in Lichens. 
Before passing to a consideration of the gross morphology of the fruits of 
lichens, it may be stated that lichens are scarcely more varied as to form, 
size and color' than many undoubted morphological units of the plant king- 
dom, and that the variations are by no means so great that these characters 
can not be depended on in the. description and determination of species and 
