Chap. III.] THE PROCESS OP AGGREGATION. 



35 



slow, and resemble those of Amcebse or of the white corpuscles 

 of the blood. We may therefore conclude that they consist 

 of protoplasm.* If their shapes are sketched at intervals of 



mm 



Fig. 7. 



(Drosera rotundifolia.) 



Diagram of the same cell of a tentacle, showing the Tarions forms saoces- 



sively assumed by the aggregated masses of protoplasm. 



a few minutes, they are invariably seen to have undergone 

 great changes of form; and the same cell has been observed 

 for several hours. Eight rude, though accurate sketches of 

 the same cell, made at intervals of between 2 m. or 3 m.. 



* [This conclusion has been 

 shown to be erroneous: there can 

 be no doubt that the aggregated 

 masses are concentrations or pre- 

 cipitations of the cell-sap, and 

 that their supposed amoeboid 

 movements are the result of the 

 streaming protoplasm, which 

 moulds the passive masses Into a 

 variety of forms. 



Pfeffer was the first to Insist 

 on this view of the nature of 

 apjrregatlon. In his ' Osmotlsche 

 Untersuchunpen ' (1877). Since 

 then the subject has been Inves- 

 tigated by Schluiper (' Bota- 

 nlsche Zeltung.' 1SS2. p. 2), who 

 deserilies the appregjited masses 

 as concentrations of cell-sjip, 

 rich In tannin, and floating in the 

 swollen and transparent proto- 

 plasm. 



Sehimper's observations are 

 confirmed by Oardlner (' Proc. 

 Royal Soc.,' Nov. 19. 1885,' No. 

 240. 1880), who describes the 

 protoplasm In the stalk-cells of 

 Drofifra dichotnma as swelling up 

 by the absorption of the " water 

 from Its own vacnole," and thus 

 leaving the tannin In cell-sap in 

 a concentrateil condition. Oar- 

 diner has addefl some curious ob- 

 servations on the connection le- 

 tween aggregation and the cn- 

 dltlon of the cell as regards tnr- 

 gtdlty. ne supposes that aggrc- 



. 4 



gatlon Is connected with a loss 

 of water, and that an aggregated 

 ceil is in a condition of dimin- 

 ished turgldlty. This Is sup- 

 ported by his observation that 

 " Injection of water Into the tis- 

 sue will at once stop aggrega- 

 tion, and restore the cell to Its 

 normal condition." These 



changes are Connected with cer- 

 tain alterations of form occur- 

 rlnir in the above-mentioned Imdy 

 described by Oardlner under the 

 name of rhabdoid, and which 

 seems to be peculiarly sensitive 

 to changes In the tarKldity, so 

 much so Indeed that the author 

 utilises It as a " turgometer," or 

 index of the degree of tur- 

 gescence. 



H. de Vrles has also written 

 on the subject of aggreeation 

 (' Botanische Zeltung,' 1880, p. 

 1), and hfs views agree with 

 those of Pfeffer, Schlmper, and 

 Gardiner as to the main fact 

 that the ncrpregated masses are 

 concentrations of cell-snp. In 

 some other respects they differ 

 from the conclusions of these au- 

 thors. 



De Vrles believes that In Dro- 

 pcrn and In vegetable cells gen- 

 era Ily the vacuoles are sur- 

 roiindetl by n special proto- 



1>lasmie wall, distinct from the 

 nyer of flowing protoplnsui 



