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UNIVERSITY OF PENNSYLVANIA, ROTHROCK
DEPARTMENT OF BIOLOGY.

JOSEPH LEIDY, M. D., LL.D., Professor of Zoology and Comparative Anatomy, Director.
JOSEPH T. ROTHROCK, M. D., B. S. Professor of Botany
HORACE JAYNE, M. D., Professor of Vertebrate Morphology
JOHN A. RYDER, Ph. D., Professor of ComparativeEmbryology
WILLIAM P. WILSON, Sc. D., Professor of Anatomy and Physiology of Plants
CHARLES S. DOLLEY, M. D. Professsor of General Biology

Philadelphia, Dec. 16 1888

My Dear Prof. Bessey:
For several years I have been collecting negatives of our American forest Trees to make lantern slides for illustration of all American Forest trees. I do not know whether you care to have anything in that line, but if you do I shall be glad to have you a sett made here in our photographic gallery at actual Cost to me. That is just what I pay the photographer 50 cts a slide. I find them very satisfactory Some other institutions have specfied a desire to have them and I thought you might possibly be of the number. There are in all about 100 slides. Most of them [fr ] My trees Negatives. Some are very fine. and none bad.
Very Truly Yours,
J. T. Rothrock