BOTANICAL SUBJECTS. 83 



j)leno^ shows a similar splittiDg up of the beii-shaped corolla oi' a 

 Convolvulus. 



Who can tell how often, in the history of the descent of a plant, 

 its flower had been subjected to this opening and closing of its 

 parts like the lamina? of a fan, or the tail of a bird. The study of 

 the different forms of leaves will leave little doubt that the 

 morphology of an immense number is nothin-g but, either a 

 fasciation of their veins by the mesophyl, or a splitting up of veins 

 into separate leaflets by flssion of the mesophyl. Entire and cut 

 leaves, palmate, digitate, pinnate, bipinnate leaves, and so forth, can 

 easily be explained by the fusion or fission of the veins which 

 malce them up. 



Fission has been also denoted by the names of chorisis, 

 dialysis, and adesmy \ while fusion has been called adhesion, 

 cohesion, fasciation, synophty, synspermy, syncarpy, synanthy* 

 and so forth. But these terms, invented by learned men, do not 

 make the cause of fusion or fission a bit clearer. They only add 

 to the trouble of the student. 



Again, polymorphy, heteromorphy, heterophylly, and poly- 

 phylly are nothing but the result of either fission or fusion. 



Whatever we may call them, there is little doubt that both 

 these phenomena have been important /ac^o?** in the modification 

 of plants, although probably not so recognized. A modification, 

 however originated, has only to be inherited to lead to further 

 and further modifications and re-arrangement of parts. 



Suppression, Abortion, and Enlargement. 



The abortion or dwarfing of certain parts of plants is a very 

 common factor in the modification of plants, as also its reverse — 

 the enlargement of parts. Among the Papilionacaai we find any 

 number of examples, in which some parts of a flower are dwarfed, 

 and others enlarged ; so in many other orders. 



The total suppression of parts is also a great factor in 

 modification. We have total suppression of petals, stamens, &c. 



As an instance of gradual suppression in the parts of the same 

 genus may be quoted that of Begonia. 



* Vide Dr. Masters " Veg. Teratology." 



