BOTANICAL ,SUBJECT>. 85 



Sometimes the mesophyl that fa.sciate.s the veins of leaves and 

 petals aborts, such as in the petals of Trichosanthes angidaa, 

 where the small petals are fringed with branched veins. 



In MusscBuda, however, one of the segments of the calyx is 

 enormously enlarged, while the remaining segments are mere 

 teeth. In "Jack-in-the-box'* Polyanthus, we have all the 

 segments of the calyx becoming enlarged, and taking on the 

 character of leaves. 



Modification of persistent organs, with altered function is 

 another source of variation. Many of the secreting organs of 

 plants are simply modification of function. 



Then we have the action of insects, birds, and animals, which 

 are factors in modifying plants. Insects have perhaps had more 

 influence in modifying flowers ; birds in modifying fruits, and the 

 large animals in modifying leaves and stems. 



Prof. Gr. Heuslow, in his " Origin of Floral Structures," 

 discusses the action of insects in distorting, amplifying, and 

 hypertrophying the different parts of a flower in search of nectar, 

 which is the only food of many species. 



In Dr. Masters " Vegetable Teratology " wiU be found a vast 

 array of what in olden times were considered monstrous forms of 

 plants, but which now are beginning to be considered as possible 

 origins of forms which are not usually called monstrous, but 

 normal, owing to their persistence through whole genera. 



The terms abortion, suppression, atrophy, diminution, dwarfing, 

 depatiperation, degeneration, stasis, arrest of development, have 

 all more or less the same meanings. They are terms invented to 

 express different degrees of diminution — from simple reduction in 

 size to total suppression, such as to leave no trace that any organ 

 had existed there in any ancestral form. 



We should look on the several parts of plants, both cellular 

 and vascular, and the whole plant, as elastic bodies. Hereditv is 

 ever struggling with the variation caused by sexual reproduction, 

 &c. The former tends to keep things as they were ; the latter is 

 always tending to change them. Being elastic, so to speak, the 

 parts of a plant, which are repeated through the fertilized seed, 

 are ever having their equilibrium disturbed, and so we find some 

 parts enlarging, lengthening, or shortening, dwarfing, and entirely 

 disappearing for a more or less long period. Adaptation to 



