HABITS OF CLIMBING PLANTS. 159 



scientific labors were interrupted by illness, — as was no less 

 the case with respect to his former papers on Dimorphous and 

 Trimorphous Flowers and his volume on the Fertilization of 

 Orchids by the aid of Insects. Of these works and of the 

 present, — side issues as they are, — it may fairly be said, that 

 they show a genius for biological investigation, and a power 

 of turning common materials and ordinary observations to high 

 scientific account, which, if equalled, have not been surpassed 

 since the days of Hunter and Charles Bell. This will be the 

 opinion equally, we suppose, of those who favor and of those 

 who dislike Mr. Darwin's theory of the gradual transforma- 

 tion of specific forms through natural selection, upon which, 

 indeed, all these collateral researches have a bearing, direct or 

 incidental. In the present case the bearing is obvious. The 

 gradual acquisition by certain plants of advantageous pecu- 

 liarities is inferred from the gradation of forms and functions. 

 Properties and powers which are latent or feebly developed 

 in most plants are taken advantage of by some, made specially 

 useful, and enhanced from generation to generation. Tendril- 

 bearing plants, the most specialized in structure and the most 

 exquisitely adapted to the end in view, are supposed to have 

 been derived from leaf-climbers, and these in turn from simple 

 twiners. 



The author states that he was led to this subject by a brief 

 note, communicated to the American Academy in the summer 

 of 1858 (and reprinted in this Journal), in which the writer 

 of the present notice recorded his observation of the coiling 

 of certain tendrils by a visible movement promptly following 

 an extraneous irritation. Mr. Darwin's observations were 

 more than half completed before he became aware that the 

 spontaneous revolution of the stems and of some tendrils of 

 climbing plants had been observed and recorded almost forty 

 years ago, and nearly at the same time, by Palm and by Von 

 Mohl, and had been the subject of two memoirs by Dutrochet, 

 published more than twenty years ago. But the mode in 

 which the free and growing end of a stem sweeps around 

 seems not to have been previously well made out, having been 

 more or less confounded with the torsion of the axis which 



