Chap. III.] THE PROCESS OF AGGREGATION. 33 



CHAPTER in. 



AGGREGATION OP THE PROTOPLASM WITHIN THE CELLS OF 

 THE TENTACLES. 



Nature of the contents of the cells before aggregation Various causes 

 which excite aggregJition The process comniences within the glands 

 and travels down the tentacles Description of the aggregated masses 

 and of their spontaneous movementsCurrents of protoplasm along 

 the walls of the cells Action of carbonate of ammonia The granules 

 in the protoplasm which flows along the walls coalesce with the cen- 

 tral masses Minuteness of the quantity of carbonate of ammonia 

 causing aggregation Action of other salts of ammonia Of other sub- 

 stances, organic fluids, &c. Of water Of heat Redissolution of the 

 aggregated masses Proximate causes of the aggregation of the proto- 

 plasm Summary and concluding remarks Supplementary observa- 

 tions on aggregation in the roots of plants. 



I WILL here interrupt my account of the movements of the 

 leaves, and describe the phenomenon of aggregation, to which 

 subject I have already alluded. If the tentacles of a young, 

 yet fully matured leaf, that has never been excited or be- 

 come inflected, be examined, the cells forming the pedicels are 

 seen to be filled with homogeneous, purple fluid.* The walls 

 are lined by a layer of colourless, circultfting protoplasm ; * 

 but this can be seen with much greater distinctness after the 

 process of aggregation has been partly effected than before. 

 The purple fluid which exudes from a crushed tentacle is 

 somewhat coherent, and does not mingle with the surrounding 

 water; it contains much flocculent or granular matter. But 

 this matter may have been generated by the cells having been 



> [The statement as to the ab- ered In Dmnera dichotoma. but ex- 

 sence of n nucleus lii the stalk- Ists also In D. rotundifolia: In 

 cells of Drosera (Francis Dar- the former species. In which It 

 win. ' Quarterly Journal of Ml- has been more especially studied 

 croseopleiil Solenee.' 1876) has by Its discoverer. It la a more or 

 been shown by I'fefTer to be qtilte less spindle-shaped mass, stretch- 

 erroneous (' Osmotlsche , TJnter- Ing diagonally across the cell, 

 Buchnntten.' 1877, p. 107). F. D.] the two ends being embedded In 



* [Mr. W. Gardiner (' Proc. R. the cell-protoplasm. " It la prcs- 



Soc.,' No. 240, 1880) has de- ent In all the epidermic cells of 



scribed a remarkable bodv the leaf except the gland cells 



named by him the " rhabdoid, and the cells Immediately be- 



whlch exists within the eplder- neath the same." Further refer- 



mlc cells of the stalk of the ten- ence to the rhabdoid will be 



tacles. This body was dlscov- found at p. 35. F. I).] 



