BARBERRIES. 791 



The nectar glands of these hypothetical outer stamens, although 

 situated behind the others, would not be disqualified in the least 

 by such a position from continuing to perform their function. 

 On the contrary, it might well happen that, as they no longer 

 produced pollen, they would secrete all the more nectar in conse- 

 quence, and thus relieve the inner stamens of so much of their 

 work. No longer required, the glandular appendages of the latter 

 would be reduced to rudiments (as in mahonias), or entirely dis- 

 appear, as we have seen in the case of the true barberries. 



Do the above considerations help us to any better understand- 

 ing of how the irritability of the stamens came to be developed ? 

 In our previous consideration of this remarkable property, we 

 saw reason to believe that such a peculiar manifestation of pro- 

 toplasmic activity could only be satisfactorily explained as hav- 

 ing resulted from a rare combination of favoring circumstances. 

 Although, in the discussion of such a matter, we are confessedly 

 treading upon uncertain ground, still, it may be worth while to 

 inquire whether, supjoosing the barberry flower to have been 

 evolved essentially after the manner indicated, there have not 

 been thus happily combined the very factors we should deem 

 necessary and adequate to produce this result. It should be 

 remembered that we are not endeavoring to account for that 

 fundamental property of protoplasm known as contractility, but 

 only for its being in the stamens of the barberry so much more 

 strikingly exhibited than in other organs of the plant, and in the 

 great majority of other plants. 



In the first place, in order that this or any other property of 

 protoplasm should be especially well shown in any organ, it 

 would seem to be a prerequisite that the organ should be unusii- 

 ally rich in protoplasm a supposition which is confirmed by the 

 comparative study of motile organs. Such a very considerable 

 reduction of parts as we believe to have taken place in the bar- 

 berry flower might well be connected with the enrichment of the 

 remaining tissues. 



Secondly, a mechanical stimulus applied repeatedly for in- 

 numerable generations, at a very definite part of the stamen, 

 would seem to be also necessary in order to account for the fact 

 that movement of the organ occurs in response to a touch only 

 when applied to the front of the filament and near its base. 

 From the position which the glands came to occupy in the flower, 

 just such a stimulus was afforded by the proboscis of every insect 

 that sipped the nectar. 



Whether we are at liberty to suppose that the direct effects of 

 such a repetition of stimuli may be accumulated through inherit- 

 ance, or whether we must assume only the inheritance of for- 

 tuitous variations, is of comparatively small consequence in this 



