CAUSES OF BARRENNESS, &C. 173 



expanded offset : in Stapelia and Cereus, where 

 there are no foliar expansions, the flowers must be 

 considered as distorted stems : in Mammalaria, 

 metamorphosed mammce, and the flowers of such 

 plants as the strawberry, must be accounted flori- 

 ferous runners. If flowers of trees be stunted branches 

 then perfect branches are runaway flowers; and if 

 sepals, petals, filaments, and pericarps be only 

 modified, contorted, and discoloured leaves, then are 

 perfect leaves only vagrant bracti, sepals, &c. c. 



Much satisfaction and amusement, no doubt, arises 

 from the study of the more occult processes of vege- 

 table transformations ; and there is much merit even 

 in the attempt to give a rational account of them ; 

 but much care is necessary to distinguish perfect 

 from imperfect, regular from irregular development. 

 When perfect, the arrangement of structure, the 

 form and functions of the several organs, and all the 

 exhibited phenomena of growth, are similar in every 

 plant of the same family ; but occasionally indivi- 

 duals differ, and fly away from the regular order of 

 development. Some accident of treatment, perhaps, 

 or peculiar circumstance arising from soil, situation, 

 or season, will cause derangement of structure by 

 reduplication of members, as in double flowers, or by 

 partial destruction or mutilation of organs. Some 

 genera have constitutional powers of metamorphoses, 

 yielding plants, instead of seed, as Lilium ; com- 

 pressed, instead of quadrangular or cylindrical stems, 

 as Asparagus, Epiphyllum, &c. These last are 



