1873.] 
Notices of Books . 
125 
The Different Forms of Flowers or Plants of the Same Species. 
By Charles Darwin, F.R.S. London : Murray. 
Though modestly proclaiming himself no botanist, Mr. Darwin 
continues to produce botanical researches whose sterling value 
must be admitted even by the most determined adherents of the 
old school of Natural History. The work before us treats of 
some very interesting points connected with the reproduction of 
plants. A certain number of vegetable species were grouped 
together by Linnaeus as hermaphrodites, and amongst these are 
a class which Mr. Darwin studied and described some years ago 
as “ dimorphic” and “ trimorphic,” and which have since been 
named “ hetero-styled ” by Hildebrand. In plants of this class 
there are individual flowers of two, or in other cases of three, 
forms, differing principally in the relative length of the pistils 
and stamens. A familiar instance may be found in thq common 
cowslip, polyanthus, and auricula. In some of these flowers 
the globular stigma appears at the mouth of the corolla, whilst 
in others the stigma does not protrude, and in its stead appear 
the anthers as an annular tuft. These different forms of the 
flower are named by florists respectively “ pin-eyed ” and 
“ thrum-eyed.” The former type is named by our author the 
long-styled, and the latter the short-styled. These two kinds of 
flowers are never found upon one and the same plant. Mr. 
D arwin has investigated the meaning of this diversity, and finds 
that it is by no means accidental or unimportant. If the long- 
styled form is fecundated by the pollen of the short-styled form, 
or vice versa, we have complete fertility ; the seed is abundant 
and good, and the author accordingly speaks of this as a 
“ legitimate union.” If, on the other hand, a long-styled flower 
is fertilised by the pollen of a long-styled flower, or if a short- 
styled flower is fecundated by the pollen of a short-styled flower, 
we have two cases of “ illegitimate union,” in which the seed 
produced is not merely much less in quantity, but inferior in 
quality. 
There are other plants, again, in which we find not two, but 
three different forms, as in certain species of Ly thrum , Nescea , 
Oxalis , and Pontederia. Here, again, we mark the same dif- 
ference between the effeCls of legitimate and of illegitimate 
union. The author remarks that there is a wonderfully close 
parallellism between the effeCls of illegitimate and of hybrid 
fertilisation. “It is hardly an exaggeration to assert that seed- 
lings from an illegitimately fertilised hetero-styled plant are 
hybrids formed within the limits of one and the same species. 
This conclusion is important, for we thus learn that the difficulty 
in sexually uniting two organic forms, and the sterility of their 
offspring, afford no sure criterion of so-called specific distinCl- 
ness. If anyone were to cross two varieties of the same forms 
