206 THE AMERICAN NATURALIST. (VoL. XXXIII. 
spurred petal. This group includes Viola heterophylla, V. lutea, 
V. tricolor, and varieties. In the remaining species the stigma is 
straight or somewhat globular and is destitute of any lip-like append- 
age, the style is bent or straight, and if any hairs are present upon 
the petals, they are straight. This group may be further subdivided 
on the length of the nectar-secreting stamenspur as follows: 
(1) Spur shorter than the anther cells.— V. blanda, V. primule- 
folia, V. lanceolata, V. palustris, V. renifolia. 
(2) Spur of the same length as the anther cells and extending 
between them. — F. rotundifolia, V. canadensis, V. nuttallii, V. hastata, 
V. pubescens, V. scabriuscula, V. tripartita. 
(3) Spur extending 1.5 to 1.8 mm. below the anther cells. — 
V. pedata, V. ovata. 
(4) Spur extending 2.3 to 3.6 mm. below the anther. 
(a) Spur 0.78 mm. wide. — V. arenaria, V. labradorica, V. striata, 
V. selkirkit. 
(6) Spur 1.5 to 1.8 mm. wide.— FV. delphinifolia, V. odorata, 
V. obligua, V. palmata, V. sagittata, V. sororia. 
(5) Spur extending 9 mm. below the anther. — V. rostrata. 
Whether these 30 are all good species or partly varieties or hybrids 
is not yet certain. Color in some species has been shown to depend 
on climate, and the same is true of caulescence and acaulescence. 
The pollen is much alike in all. In some cases systematists appear 
to have mistaken germinating pollen grains for hairs in the bottom of 
the flower. The shape of the mucilage cells may possibly turn out to 
be of some help in classification. They are readily stained in a solu- 
tion of methylene blue. The author would be glad to monograph 
this genus, if material could be obtained. He desires fresh seeds of 
Viola from all parts of the world. His address is Philadelphia College 
of Pharmacy, Philadelphia, Penn. 
Dr. G. E. STONE: The Influence of Electricity upon Plants. —- V ari- 
ous kinds of currents were employed and data showing the relative 
effect of each upon the growth of the plant were presented, also the 
effect of single stimuli for a period of one minute, hourly intermittent 
and constant stimuli were shown. A brief résumé of some of the 
more important results obtained by subjecting about 20,000 plants 
to electrical stimuli are as follows: 
(1) The application of certain strengths of current for a short 
period of time (one minute or less) is sufficient to act as a stimulus. 
