62 DROSERA ROTUNDIPOLIA. [Chip, IIL 



cles ; * but the casc?s above given are somewhat different, as 

 they relate to the delay in the generation or aggregation 

 of the masses of the protoplasm by the exclusion of oxygen. 



Summary and Concluding Remarks. The process of 

 aggregation is independent of the inflection of the tentacles 

 and apparently of increased secretion from the glamls. It 

 commences within the glands, whether these have been di- 

 rectly excited, or indirectly by a stimulus received from 

 other glands. In both cases the process is transmitted from 

 cell to cell down the whole length of the tentacles, being 

 arrested for a short time at each transverse partition. With 

 pale-coloured leaves the first change which is perceptible, 

 but only under a higher power, is the appearance of the 

 finest granules in the fluid within the cells, making it 

 slightly cloudy. These granules soon aggregate intp small 

 globular masses. I have seen a cloud of this kind appear in 

 10 s. after a drop of a solution of carbonate of ammonia had 

 been given to a gland. With dark red leaves the first visible 

 change often is the conversion of the outer layer of the 

 fluid within the cells into bag-like masses. The aggregated 

 masses, however they may have been developed, incessantly 

 change their forms and positions. They are not filled with 

 fluid, but are solid to their centres. Ultimately the colour- 

 less granules in the protoplasm which flows round the walls 

 coalesce with the central spheres or masses; but there is 

 still a current of limpid fluid flowing within the cells. As 

 soon as the tentacles fully re-expand, the aggregated masses 

 are redissolved, and the cells become filled with homo- 

 geneous purple fluid, as they were at first. The process of 

 redissolution commences at the bases of the tentacles, thence 

 proceeding upwards to the glands; and, therefore, in a re- 

 versed direction to that of aggregation. 



Aggregation is excited by the most diversified causes, 

 by the glands being several times touched, by the pressure 

 of particles of any kind, and as these are supported by the 

 dense secretion, they can hardly press on the glands with the 

 weight of a millionth of a grain,* by the tentacles being 



* with resppct to plnntn Snobn, Acoorrtlnjr to Hofmolster (as 



Trnltft de Rot..' 3rrl. wilt.. 1874, quoted bv .Sachn. ' Trnit* de 



p. K4fl. On l)lood corpiiKclM. tfe Bot..' 1874. p. 958). rpry Blljrht 



'(jiiartorly JournnI of Sllcroncopl- proHnnre on tho oell-monil)rane 



cal Science,' April 1874, p. 185. arrests Immediately the move- 



