REPRODUCTION. 187 



propagated from stolons, runners, corms, etc. Should these latter 

 means of propagation fail to appear, the plant could, nevertheless, 

 continue its existence. 



At first glance the above general considerations and statements 

 in regard to reproduction may not seem to have been very fortu- 

 nately chosen. However, the student on entering more deeply 

 into the phenomena coming under this category will soon recognize 

 that the foregoing introductory statements, in which the author has 

 followed KAGELI'S concept of the subject, are sufficient to place the 

 essentials of the endless variety of phenomena under a few com- 

 prehensive heads. 



Germ-formation is very frequently sexual, as has already been 

 stated. The male and female organs, which are essential in this 

 form of reproduction, permit of the recognition of three different 

 forms, dependent upon the relative position of these organs. 



1. Hermaphroditism : male and female organs are in imme- 

 diate proximity, for example, in phanerogams in the same flower ; 

 or on the same axis (among vascular cryptogams on the same pro- 

 thallium). 



2. MonoBcie : male and female organs are on the same plant,, 

 but on separate axes ; that is, the flowers are unisexual. 



3. Diweie : male and female organs are distributed upon dif- 

 ferent individuals of the same species. 



A large number of flowers are hermaphroditic (perfect, bi- 

 sexual), for example, our cereals, fruit-trees, legumes, the poppy, 

 etc. ; the birch, oak, hazelnut, and most conifers are monoecious ; 

 willows are dioecious. Monoacie and dioecie occurring together 

 form didiny. 



Before entering upon the special discussion of the phenomena 

 of reproduction it is important to introduce an observation on 

 systematic botany. The essentials of our plant-system are taken 

 from the domain of reproduction, and w r e may add that, as far as 

 mosses, vascular cryptogams, gymnosperms, and angiosperms are 

 concerned, it is more than probable that no other factors will sup- 

 plant in importance those of reproduction. Algae and fungi are 

 separated from each other by the presence or absence of chloro- 

 phyll, and both are separated from the leafy mosses by the absence 

 of leaf and stem ; but within the algal and fungal groups them- 



