July 1900.] BOTANICAL SOCIETY OF EDINBURGH 329 



but rather, at least iu its more important aspects, the 

 stimulation of the protoplast to an increased vital activity 

 leading up to the development of the zymogen itself, 

 which, in its turn, under the influence of the same rays, 

 becomes converted into a zymase, by which the absorption 

 of the stored food materials is rendered possible. 



LITERATURE REFERRED TO. 



1. Stebler. — Ueber der Einfluss des Lichtes auf die Keimuug.- — Bot. 



Centralbl., vii. Bd. p. 157. 1881. 



2. Cieslar, Ad. — Untersuch. u. d. Eiufluss d. Lichtes a. d. Keimung d. 



Samen. — Forscluuigen auf des Gebiete der Agricultur Physic, 

 vi. Bd. 1893. 

 o. Heinricher, E. — Ein Fall beschleunigter Wirkung d. Lichtes a. d. 

 Samenkeiinung. Yorlauf. ^litth. — Ber. d. D. Bot. Gesellschaft. 

 Jiihrg. xvii., H. S pp. 308-016. 1899. 



4. Forest Heald. — Conditions for the Germination of the Spores of 



Bryophytes and Pteridophytes. — Bot. Gaz. xxvi. pp. 25-45. 

 1899. 



5. Bokoruy, Th. — Einioes iiber die Proteinstoffe der Samen. — Bot. 



Centralbl. Ixxxii. Bd., No. 10, 11, p. 289. 1900. 

 G. Green, J. R. — On tlie Action of Light on Diastase and its 

 Biological Significance. — Phil. Trans. Bot. vol. clxxxviii. 1897. 



7. Klebs, G. — Ueber d. Organisation d. Gallerte b. Einigen Algen u. 



Flagellaten. — Untersuch. a. d. bot. Inst. z. Tubingen. 



8. Balfour, B. — Botanical Lecture Exijerimect. — Nature, vol. xxxv. 



p. 126. 1886. 



Notes on the Potentille.e. I. — The Flower. By E. A. 

 EoBERTSON, M.A., B.Sc. (With Plates.) 



(Read 12th July 1900.) 



On account of their variability, the Potentillas have 

 always been a confusing group, and the statements made 

 by systematists as to the number of species differ widely. 

 Nestler ("Mouographia de Potentilla") in 1816 enumerated 

 68 species, and varieties in addition. The shapes of the 

 leaves and the characters of the torus were utilised for 

 the subdivisions of the group. In De Candolle's " Prodro- 

 mus " (1825), the genus Potentilla is included in the tribe 

 Dryadere of the Piosacete. 106 species, besides sub-species 

 and varieties, are described. The genus is subdivided into 

 three sections, based on such characters as the colour and 

 shape of the petals, as well as the manner of branching 

 of the foliage leaves. 



TKANS. HOT. SOC. KDIX. VOI.. XXI. Z 



