222 THE BOTANISTS OF PHILADELPHIA. 



Moravian Seminary for Young Ladies, at Bethlehem, Penn- 

 sylvania. In 1861 he became Principal of the institution, 

 and conducted its affairs with marked ability until 1881, 

 when the increasing infirmities of age necessitated his 

 seeking rest. 



From his childhood the study of natural history was 

 his favorite pursuit, and after his retirement from active 

 professional work in 1881, he devoted himself to it with more 

 ardor than ever. He was especially known among botanists 

 as an authority on fresh-water algse and desmids. In 

 1884 he published his " Desmids of the United States and 

 List of Pediastrums.* The volume contained 1100 illustra- 

 tions on fifty-three colored plates. This was followed in 1887 

 by two volumes on " The Fresh-water Algae of the United 

 States, complimental to Desmids of the United States."t 

 This work was illustrated by 117 colored plates, embracing 

 2300 figures. In 1891 he brought out a work the 

 " Diatomaceee of North America." % This contained 2300 

 figures on 120 plates. All of the illustrations enumerated 

 were photo-lithographs from India-ink sketches made by the 

 author. During 1892 there appeared a revised and enlarged 

 edition of the " Desmids of the United States." 



His contributions to cryptogamic botany are recog- 

 nized b}^ scientists at home and abroad as standard works 



* "Desmids of the United States and List of American Pediastrums,'' ivith 

 eleven hundred illustrations on fifty-three colored plates, by the Rev. Francis Wolle, 

 Bethlehem, Pennsylvania. Moravian Publication OflBce, 1884, pp. xiv, 168. 



t "Fresh-water Algce of the United States {exclusive of the Diatomacece) com- 

 plimental to Desmids of the United States," with 2300 illustrations covering one Jiun- 

 dred and fifty-one plates. A few colored, including nine additional plates of 

 Desmids, by the Rev. Francis Wolle, Bethlehem, Pennsylvania. The Comenius 

 Press, 1S87. 



I "Diatomacece of North America." Illustrated with twenty-three hundred 

 figures, from the author's drawings, on one hundred and twelve plates, by the Rev. 

 Francis Wolle, Bethlehem, Pennsylvania. The Comenius Press, 1890. 



