KINETOGENESIS. 383 



Several years ago Prof. August Miiller and I called 

 attention nearly simultaneously to the probability that 

 many of the forms of the reproductive organs of plants, 

 especially the flowers, are due to the strains and other 

 effects produced by their use by insects. Rev. George 

 Henslow has written a book in which this subject is 

 set forth in detail. 1 It is impossible to demonstrate 

 this point with the same certainty as the kinetogenetic 

 origin of the articulations of the vertebrate skeleton 

 and their characters, owing to the absence of paleon- 

 tologic evidence. Henslow, however, says: "When 

 we find innumerable coincidences all tending in one 

 direction, coupled with an indefinite capacity for vary- 

 ing in response to forces in all parts of plants, I still 

 maintain that [this] theory does not utterly break 

 down," as asserted by Mr. Wallace. 2 Wallace argues 

 that since many regular flowers have been subject to 

 the irritation of insects and have not become irregu- 

 lar, there is no reason to suppose that this is the cause 

 of the irregularity in question. To this Henslow re- 

 plies: 3 [Mr. Wallace] "will see that existing regular 

 flowers being mostly terminal, have no lower petals at 

 all, but are so situated as to offer access to insects 

 from all points of the compass. Moreover, when a 

 plant with normally irregular flowers (which are always 

 situated close to the axis, so that insects can only en- 

 ter them in one way) produces a blossom in a terminal 

 position (as foxglove, larkspur, horse-chestnut, etc., 

 often do), it at once becomes quite regular." This 

 change may be brought about artificially, for, says 



1 The Origin of the Floral Structures by Insect and Other Agencies. Inter- 

 national Science Series, Vol. LXIV. 



^Natural Science, 1894, p. 178. 

 ^Natural Science, 1894, p. 262. 



