208 Dr Daubeny on (he Wntings and 



are considered as natural to it ; 2dly, An alteration in its 

 structure, and consequently in its functions ; ^dly. The union 

 or coherence of several organs, so as to appear like one. 



" These causes are ranked by DecandoUe under the three 

 general heads of the abortion of organs, their degeneration, 

 and their mutual coherence ; and any one of them may be 

 considered competent to induce such a change in the general 

 appearance of a plant, as shall render it altogether different 

 from another to which it would, on general grounds, appear to 

 be closely allied. 



" That particular organs in plants do frequently become 

 abortive, in consequence of the common accidents of excessive 

 or defective humidity, light, fcc, had been before admitted ; 

 but to Monsieur DecandoUe we are indebted for assigning a 

 wider influence to this cause, and for shewing, that in many 

 cases there are forces in regular operation which produce a 

 constant alteration in, or obliteration of, certain parts. 



" If, indeed, we admit, that such effects may and do arise 

 from internal as well as from external causes, from the effect 

 of the mere growth and development of parts connected with 

 its own structure, as well as from the operation of foreign 

 agents, it is plain that they would extend, not to a few only, 

 but to all the individuals belonging to the family of plants 

 possessing the kind of structure which occasions it. 



" Thus, for example, we observe in the horse-chesnut three 

 seed-vessels or carpels, each containing two seeds ; whilst in 

 the fruit we perceive in all never more than three seeds, and 

 sometimes only a single one. It is evident, therefore, that at 

 least three of the seeds have died away, not from any cause 

 which can be considered accidental, but from something inhe- 

 rent in the very structure of the tree. We may indeed trace 

 the gradual decay of these abortive seeds, by opening the seed- 

 vessel at different stages of its growth. In like manner it is 

 found to be the rule, that in some cases the terminal, in others 

 the lateral buds, will arrive at maturity ; but, that the abor- 

 tion of the one arises merely from the development of the 

 other, and not from any inherent peculiarity of structure in 

 itself, has been proved, by removing the bud, which commonly 

 expands at an early age, by which means the one which is 



