112 THE STEUCTUKE OF FLOWERS. 



ing the insect. Such is the case in the Ocimoideoe of Lahiatce, 

 in Gollinsia bicolor, the " Letnon-scented " Pelargonium, etc. 



Correlation of Growth. — I have only referred to the 

 forms of flowers as grouped under the terms "regular" or 

 " irregular," and alluded to a few instances ; for it is not my 

 object in this work to merely give illustrations of various 

 kinds, -which are presumably well known to the reader, but 

 to ofBer a rationale of the whole, without, however, attempt- 

 ing to say how each individual shape has actually come into 

 existence. To do this, it would be impossible in the present 

 state of our knowledge of the history of flowers ; my object 

 being to suggest a probable cause, namely, the mechanical 

 influence of insects, without excluding others which we 

 cannot trace. Nutrition, however, must be always borne in 

 mind as an important one, hereditary influences as others — 

 as, for example, in the restoration of an irregular flower to a 

 condition of regularity, as occurs in Linaria, Lamium, Glox- 

 inia, etc. The point, however, which I ■would specially 

 emphasize is the correlation existing between the several 

 parts of the organs, so that, regai-ded collectively, they all 

 conspire to secure one and the same end, that being the 

 pollination of the flower. Thus, as I have shown above, the 

 calyx of Salvia has a form and structure correlated to the 

 tube of the corolla; the corolla has a form in strict adapta- 

 tion to the weight and pressures of the insect which rests 

 upon the lip. The stamens are, again, correlated to the pres- 

 sures brought to bear upon them, and have grown in 

 response, forming the remarkable lever-processes, 'which are 

 also found in species of Calceolaria. Lastly, the style and 

 stigma ai'e correlated to the position of the anthers. Hyper- 

 trophy in one direction has brought about atrophy in 

 another, so that the two posterior stamens, are rudimentary, 

 while the fifth has vanished altogether. 



