OEGANS OF REPRODUCTION. 



51 



iSj however, not a constant character, dioecious plants 

 often proving to be monoecious. 



The above are the principal forms which, in accordance 

 with our ideas, represent what are called types of nature's 

 rule of construction, and any deviation from the above 

 may be looked on by some as freaks of nature but this 

 is not admissible, for the most odd and grotesque forms 

 in orchids, aristolochias, and others, are as typical of 

 nature's rule as the most regular flowers, all those forms 

 which appear as irregularities being brought about by a 

 mere difference in size and form, or by a suppression of 

 one or more parts. This may be seen by comparing 

 the flowers of the pea, bean, or scarlet-runner^, with 

 those of the cherry, plum, peach, or almond; the same 

 number of parts will be found in each, and having the 

 same position with regard to one another ; but in the pea 

 the petals are of various forms, and so placed as to give 

 the appearance of being irregular as compared with the 

 cherry, or as an orchid is to a tulip or lily. 



Fertilization, and its Eesults. 



Whatever may be the form or number of parts in a 

 flower, it must be admitted that they are intended by 

 nature as aids in a process for accomplishing the final 

 destiny or purpose of a flower, which is to generate, or- 

 ganize, and perfect certain bodies containing the embryo 

 of a future plant, called the seed. This object is attained 

 by a process common to all flowers, viz. by one or 

 more grains of pollen coming in contact with the stigma, 

 which takes place either by the contiguity of the parts, by 

 gravity, by motion of the air, or by what may be called 

 mechanical aid, the agents in the latter case being chiefly 

 insects ; or by the elastic spring of the stamens, as in the 



E 2 



