BRAINERD: FOUR HYBRIDS OF VIOLA PEDATIFIDA 251 
that have the compromise leaf reproduce plants with three forms 
of leaf incision, as did the original hybrid. Also in the relative 
number of these forms there is an approximation to the Mendelian 
ratio 1 :2:1. In the above 26 plants (broods 236 and 468), 
whose forms were verified by their offspring, there are 9 A’s, 
11 Aa’s, 6 a’s, the theoretical ratio being: 63 A’s, 13 Aa’s, 63 a’s. 
In the 169 offspring of Aa plants, given above for the third and 
fourth generations, there are 44 A’s, 84 Aa’s, 41 a’s, the theoretical 
ratio being: 42} A’s, 844 Aa’s, 42} a’s. Here we find, as usual, 
that the larger the number of individuals the closer the normal 
ratio is realized. 
But besides general conformity there are also departures from 
the strict Mendelian law. For one thing the hybrid or inter- 
mediate leaf varies in different individuals, inclining now more to 
the form of the one parent species and now more to the form of the 
other. Also the reversionary forms, designated as A and a, are 
rarely complete reversions. The A plants, though stable in 
producing like parted leaves in succeeding generations, do not 
have leaves as deeply parted as in V. pedatifida; and the a plants, 
though plainly uncut and stable, usually have teeth noticeably 
longer than in normal V. papilionacea, sometimes even pectinate. 
(PLATE 15, FIG. a.) 
Another cause often conspires to increase these differences in 
leaf pattern: the presence of minor hybrid characters that inde- 
pendently adjust their special conflicts of hybridity. For example, 
the leaf of V. pedatifida is usually truncate or even cuneate at the 
base, that of V. papilionacea usually cordate. A hybrid offspring 
may inherit the broad truncate base of the former with the uncut 
margin of the latter. Sometimes in the hybrid leaf the lobes are 
entire, and obtuse at the tip; sometimes, as in the normal leaf of 
V. pedatifida, the lobes are again cleft or toothed on the outer 
margin, and acute at the tip. 
In these various ways there han arisen in the numerous progeny 
of the hybrid under discussion a considerable diversity of foliage, 
such as would present insoluble difficulties to a taxonomic student, 
who did not know that these diverse forms all came from one 
individual, by close-fertilized reproduction, in the short period 
of three or four years. The extreme differences are such as would 
