216 Rhodora [ NOVEMBER 
hybrids. As pointed out by Dr. McDougal,' the test of a suspected 
natural hybrid may often be better made by the Method of Analysis 
than by the Method of Synthesis. In the genus Viola the analytic 
method has proved unexpectedly successful. Over thirty putative 
hybrids have produced offspring that segregate in accordance with 
Mendelian principles. 
An objection recently made to the occurrence of hybrids in Viola is 
based on the supposed fact “that 99 out of 100 seeds of these plants"? 
are from self-fertilized flowers. This led me last June to examine 
with reference to this matter plants of some eighteen species of our 
stemless violets, and revealed the fact that all but two of these plants 
produced seed freely from the petaliferous flowers; in some instances 
over 300 such seeds were produced by a single plant? The structure 
of the flower, in style stamens and petals, shows a most ingenious 
arrangement to prevent self-pollination; and it is now evident that 
the ovules are readily fertilized by the pollen of an allied species. The 
coexistence of this habit with the opposite habit of producing in sum- 
mer self-fertilized flowers is apparently the cause of the multiplicity 
of forms in this group of plants. Hybridism gives rise to numerous 
intergradient types; cleistogamy preserves them from further inter- 
mixture more skilfully than the artificial hybridizer with his paper 
bags, and permits the laws of Mendel to work out their natural results, 
giving rise often to new varieties and races. The behavior of violet 
hybrids and their offspring under cultivation presents many striking 
illustrations of this procedure, and awakens the hope that with this 
clew to guide us we may solve some of the long-standing perplexities 
of the genus. 
MIDDLEBURY, VERMONT. 
1 Hybridization of Wild Plants, Bot. Gazette xliii. 11-44, Jan. 1907. 
? Prof. E. L. Greene, Leaflets i. 214. 
3 Five plants of V. nephrophylla furnished at one time from the capsulés of petaliferous 
flowers 1227 ripe seeds. 
