v.] ADAPTATIONS TO FORCES 43 



in concentric cylinders, these being practically 

 a combination of girders, the pith being the 

 " web," and its frequent absence by decay being 

 a matter of indifference, as the cylinder is then 

 simply a hoop with a " tire " consisting of the 

 whole length of the stem in width. On the 

 other hand, the support of a liane or climber 

 being extraneous, the stem degenerates. It 

 may be observed that a young liane has 

 cylindrical wood for a year or two, but acquires 

 the characteristic anomalies on climbing. 



These facts quite dispose of Huxley's con- 

 tention that 



" one-half of Lamarck's arguments were obsolete 

 in 1850, and the other half erroneous or defec- 

 tive, in virtue of omitting to deal with the 

 various classes of evidence which had been 

 brought to light since his time. Moreover, his 

 one suggestion as to the cause of the gradual 

 modification of species effort excited by change 

 of conditions was, on the face of it, inapplic- 

 able to the whole vegetable world." 1 



If we assume that the degradations of climb- 

 ing stems (i.e., as compared with self-supporting 

 erect stems of non-climbers or as of timber) arose 

 in anticipation of the stems becoming climbers 

 by accidental or spontaneous variations, the 

 supposition remains to this day an unproven, 

 a priori assumption. But when we see that 



1 " Life and Letters of Charles Darwin," vol. ii v p. 189. Huxley, 

 unfortunately, was not a botanist. 



