244 
Figs. 3, 4, 5. Successive stages in the development of the antheridium ; >x 400. 
Fig. 6, a. Full grown antheridium; >< 300; b. stalk showing three rows of cells; 
< 400. . 
Fig. 7._ Three cross sections from the upper part of an antheridium; a. toward’ 
the apex; b. c. lower down ; < 400. 
Fig. 8. Cross sections from the lower part of an antheridium, d. being the lowest 
segment; 400. 
Fig. 9. Cross section of a full grown antheridium near the center; >< 400. 
Fig. 10. a. Full grown spermatozoid; b. sperm-cell with nearly developed sper- 
matozoid. 
Notes on Potentilla.—l. 
By P. A. RYDBERG, 
The author has been studying the genus /o/entilla for some 
time. The plan is to prepare a revision of the North American 
Potentilleae and have it published as Volume 2 of the Memoirs 
from the Department of Botany of Columbia College. It is 
planned to contain, if possible, full size illustrations of all native 
species of Potentilla, Horkelia, Ivesia, etc. The best way the au- 
thor knows of, to secure the codperation of other botanists is to 
publish some of the results already obtained. He will regard it as 
a great favor to be permitted to look over and name any collection 
of North American species, and will be very thankful for any in- 
formation, suggestion or criticism that may be given. , 
It will be seen from the following that my opinion as to the 
limitation of the species differs widely from those expressed in 
our manuals and from Dr. Watson's revision of Potentilla inthe Pro- 
ceedings of the American Academy of Arts and Sciences, 8: 549- 
573. They agree, however, very closely with those held by | 
the late Dr, Christian Lehmann, of Hamburg. This eminent bot-_ 
anist after having studied the genus about forty years, having 
published several papers on it from time to time, among others a 
monograph in 1820, and having prepared the text for the genus 
Potentilla in Hooker’s Flora Boreali-Americana, issued in 1856 his 
“Revisio Potentillarum,” a quarto of 250 pages and 64 plates. 
This book, which always will remain as one of our standard 
works, will serve as the basis of my revision. 
