148 THE STEUCTUEE OF FLO WEES. 



pated, that tissues will behave alike in both kingdoms ; that 

 organs will grow with use and degenerate with disuse ; that 

 they will develop processes to meet strains put upon thena, 

 as the limbs of animals have done and as stems * will do by 

 forming special tissues ; and, on the other hand, that they 

 will ati-ophy if not called upon to display their powers, as 

 parasitic organisms abundantly show in both kingdoms ; and 

 as plants degenerate in water, which saves them the trouble 

 of supporting themselves. 



All this is exactly what one finds to be the case in every 

 department of the animal and vegetable kingdoms alike, 

 whenever we search diligently into the anatomy and meaning 

 of the histological details of all parts of organisms. 



COKEELATIONS OF FlOEAL NeCTAKIES WITH POLLINATION. 



There is yet another point observable in glands. As the 

 position of a gland or nectary is just where it is most easily 

 accessible to the particular insects which visit the flower — 

 a fact abundantly illustrated throughout the floral world, — 

 and since the sole use of it to the plant, as far as we can 

 see, is that it should attract insects which transfer the pollen 

 from one flower to another, one naturally looks to see if 

 the positions of the anthers and stigmas are in any way 

 correlated to that of the honey-gland. Such is, in fact, 



• I would throw out a suggestion that the anomalous stems of 

 climbers, which often develop supernumerary collateral axes, but all 

 coherent in one common stem, may be due to a response to the strains 

 to which these stems are subjected, occurring in various directions, as 

 they hang dependent on other trees. Other peculiar features, as of 

 innumerable vessels, feeble wood tissues, etc., I take to be due to 

 degeneracy, through these stems not being self-supporting, so that they 

 have assumed very much the anatomical characters of subterranean 

 roots. Again, just as the pericycle plays so important a part in the 

 structure of many roots, it will be found that this same active layer is 

 the parent of at least several of the above-mentioned supemnmerary 

 tissues in climbers, as in the tendrils of Citcv/rbita, Bryonia, etc. 



