Tue Microscope. 263 
light fall, therefore, parallel to the principal axis of the crys- 
tals, and are dispersed on all sides from their reflecting surfaces, 
while those which pass through the crystals are refracted ob- 
liquely. It is possible that the subepidermal cystoliths in the 
leaves of Ficus have a similar property. 
EXCHANGES. 
(Exchanges are inserted or this page without charge. Subscribers having 
microscopic apparatus for saleor exchange can announce the same without charge), 
ISTOLOGICAL and Pathological slides to exchange for other good 
slides. F. F. COLWELL, Uibana, Ohio. 
RESH-WATER ALG4&, nearly all genera, and many beautiful vari- 
eties; also euglena, astasia, etc., for good pathological or other inter- 
esting slides. Lists exchanged. J. M.ADAMS, Watertown, N. Y. 
OULD like to exchangea + Bausch & Lomb patent adjustment (glyc- 
erine front) objective, almost new, for a14 of moderate angle, C. B. 
HIGBY, Mokelumne Hill, Cal. Co., California, 
HAVE a first-class black glass rotating stage, with sliding object carrier 
kept down by ivory pointed screw. Will exchange for a low power ob- 
jective, works on microscopy, or first-class mounted objects, HAROLD 
PLOWE, 1386 High St., Peoria, Ill, 
ANTED.—Diatoms on Alge, from the Sandwich Islands, Californian 
coast, and other tropical sea coasts. Will give in exchange either 
very good mounted micro-slides or cash for good material. J. C. PRINN- 
BOCH, 14 Simmering, Wien, Austria. 
OR SALE.—A copy of Prof. Leidy’s great work on the Rhizepods has 
been left at this office for sale. Price $7.50. C. H.STOWELL. 
WILL exchange good, histological for other first-class mounts. S. G. 
SHANKS, M. D., 547 Clinton Avenue, Albany, N. Y. 
ISTOLOGICAL mounts to exchange for other good slides. T. B. 
STOWELL, Ph. D., Cortland, N. Y. 
} ISTOLOGICAL SLIDES, very thin and evenly cut, well mounted and 
well ringed, will be exchanged for Pathological or Histological 
slides only. H. L. WHITNEY, M. D., German Hospital, Phila., Pa. 
ALMSLEY’S Photo-Micrographic Camera and Plate-Holder, together 
with tbe Chemical and Printing outfits, and a Darlot’s Focusing 
Glass, for sale. Also, Sidle’s [ris Diaphragm, with society screw tor sub- 
stage; Beck’s t in. and in. Objectives (National); Bausch & Lomb’s 2 in. 
Objective. F. J. SCHAUFELBERGER, M.D., Fostoria, Ohio. 
