HEREDITY, AND THE ORIGIN OF SPECIES. 2I 
hybrids. Thus when the blue-flowered Veronica longifolia 
was crossed with a white-flowered variety derived from it, 
the progeny was entirely and continuously blue-flowered 
except for occasional bud-sports. The white-flowered condi- 
tion was here very evidently in a latent condition. In other 
instances white-flowered forms have appeared as a reces- 
sive, forming one-fourth of the progeny. If qualities have 
a cytological basis, and we may certainly assume that they 
do, then it is not easy to speculate intelligently on the 
probable condition of latent characters. 
A very striking feature of mutants consists in the fact 
that the gross anatomical characters in which they diverge 
irom the parent shows a much wider range of variability 
around its new norm, than does the homologous character 
in the parental type. Many observations bearing this inter- 
pretation have been on record for sometime. Chas. Darwin 
in his Origin of Species noted that varieties varied more 
widely than the closely related species from which they 
were supposed to be derived, and many other observers 
have touched in one way or another upon the subject. Dr. 
Shull’s recent researches upon this subject led him into 
the making of exact measurements, by which he also finds 
that the wide fluctuations of the mutant characters are ac- 
companied by a lesser degree of correlation than prevails 
in the parental forms. Thus, for instance, the leaves of 
rubrinervis not only vary relatively more in width than 
those of the parental Lamarckiana, but the proportion 
between the width and length is not so constant as in the 
latter. Other organs of these and other species were sub- 
jected to exact measurements with similar results, while 
a large number of recent observations are known which 
justify the conclusions just stated. Of these the great vari- 
ation of the length of the pistil in brevistylis in comparison, 
and the wide fluctuations in laciniate leaves are good ex- 
amples. Many’of the latter are known to be direct deriva- 
