THE FLORAL STEM. 747 



receptacle has been formed, the end of the axis is overtopped by the edge of the 

 cup, and the actual apex of the receptacle must be sought at the bottom of the 

 cup. The stamens and perianth-leaves then spring in most eases from the edges 

 of the cup. In many instances the carpels also arise from the edges and cover 

 over the crater-like depression of the receptacle. More frequently the carpels are 

 developed at the bottom or on the inner walls of the cup, and then either a single 

 caj-pel is to be seen in the depression, as, for example, in cherry flowers, or several 

 carpels, as, for example, in the rose. Sometimes the pistil developed at the bottom 

 of the cup-shaped receptacle is fused with the inner wall of the cup, as, for 

 example, in the flowers of apple and pear trees. 



The disc-shaped receptacle is not, as in the examples selected, always developed 

 symmetrically all round. In flowers which project laterally from an erect rachis, 

 the circular wall is often interrupted, or instead of the circular disc a one-sided 

 projecting ridge or cushion is seen. The ring is often replaced by a circle of pro- 

 tuberances or papillae, or the receptacle is drawn out on one side, taking the form 

 of a peg, a tongue, or a scale. 



Honey is usually secreted from that tissue of the disc-shaped receptacle 

 which does not pass over into perianth-leaves, but which projects and is inserted 

 between the whorls of perianth-leaves, stamens, and carpels in the form of knots, 

 warts, cushions and rings; this serves to attract insects whose visits are of use 

 to the flowers in efiecting fertiUzation. The part of the receptacle which is 

 developed as the under-structure or envelope of the carpels, on the other hand, 

 very often becomes a part of the fruit. In most cases, however, the signifi- 

 cance assigned to the various developments of the receptacle in respect to the life 

 and welfare of plants is not yet rendered sufiiciently evident. That the rela- 

 tions between receptacle and fruit-formation are of the greatest importance is the 

 only thing that can be affirmed with certainty, but why in one instance this and 

 in another that form of receptacle is produced i-emains entirely enigmatical. The 

 opinion has been repeatedly stated that all the architectural conditions of plants 

 are not necessarily beneficial, and that the forms in which the individual organs 

 and plant members appear fall into two groups — those whose use to the species 

 in question is obvious, and those in which this is not the case. The former were 

 said to be variable, the latter invariable. This hypothesis was forthwith raised 

 to a dogma, and it was further concluded that only structures whose significance 

 in the life of plants cannot be explained are of use in the limitation and systematic 

 determination of species and groups of species. I cannot justify this notion, and 

 maintain rather that nothing is ever formed in a plant which is not beneficial, which 

 is not even indispensable to it. Those organs which are so often termed " reduced " 

 are not without importance in the life of plants ; they are rather developed in 

 this only apparently-reduced form for the welfare of the whole, and cannot be 

 dispensed with without injury. If they were unnecessary, they would also be 

 absent. The plant builds up nothing superfluous, and no hair, no cell even, is 

 developed without some purpose. It is hazardous and unwarranted to say that 



