,, DISTRIBUTION OF SEXES. 291 



Linnseus described 20 out of the 23 Classes of Phanerogams as hermaphrodite. 

 He considered hermaphrodite flowers generally to be the rule, and thought them 

 more complete than the unisexual. He connected their prevalence directly with 

 the formation of fruit, and believed the presence of stamens and pistils in the same 

 flower could be explained most simply and naturally by the fact that fertilization 

 could be performed much more easily when the receptive and fertilizing organs 

 were in immediate proximity than when they were widely separated, and thus the 

 formation of seeds capable of germination be best ensured. In a word, the idea 

 originated and found expression afterwards as an actual doctrine that fertilization 

 begins in hermaphrodite flowers by the transference of the pollen on to the stigma 

 of the same flower, i.e. that the process occurs which we now call autogamy or 

 self-fertilization. More recent researches, however, have shown that many plants 

 are only apparently (or pseudo-) hermaphrodite; that stamens and carpels indeed 

 stand close together in their flowers, but that the pollen-grains in the anthers are 

 not properly developed and have lost their fertilizing capacity. In other flowers, 

 regarded as hermaphrodite, the ovules are so altered that they are unable to develop 

 into seeds capable of germination. It has also been shown that plants provided 

 with both unisexual and hermaphrodite flowers, which Linnseus called polygamous 

 and placed in the 23rd Class, occur much more frequently and in much greater 

 variety than was formerly supposed. There is a long series of forms, one limit of 

 which is constituted by plants with truly hermaphrodite flowers, and the other by 

 dioecious plants. It is impossible, for want of space, to give an exhaustive descrip- 

 tion of all the members of this series ; but since it is important, for the sake of 

 what follows, to obtain as clear an idea as possible of this matter, the chief 

 members of the series at any rate will now be enumerated. 



At one end of the series, then, are the bisexual flowers. They always contain 

 one or several stamens besides the ovary. In the ovary are developed the ovules 

 which after successful fertilization become seeds capable of germinating; whilst the 

 anthers of the stamens contain pollen grains which have the power of fertilizing. 

 These flowers are termed hermaphrodite and it is desirable to emphasize the 

 expression by speaking of them as truly hermaphrodite flowers. 



The unisexual flowers come next. In these only one of the two sets of organs 

 which take part in fertilization is fully matured and able to perform its function. 

 When only the pistil is present, with ovules capable of development, and the 

 stamens do not mature or are entirely absent, the flowers are called female or 

 pistillate; flowers which contain stamens only, with fertile pollen, whose pistil does 

 not mature or is altogether absent, are termed male or staminate. Four kinds of 

 unisexual flowers may be distinguished: (1) Pistillate flowers which appear herma- 

 phrodite. In these pistil and stamens are present, and these flowers therefore seem 

 at first sight to be bisexual. Their pistil contains ovules which can be fertilized 

 and are capable of development, but the cells which are formed in the tissues of the 

 anthers have no fertilizing power. (2) Staminate flowers which appear herma- 

 phrodite. These are the counterpart of the flrst group. They also contain both 



