Section IV, 1917 [133] Trans. R.S.C. 



The Colloidal properties of protoplasm: Imbibition in relatio7i to growth} 



By Francis E. Lloyd, F. R.S.C. 



(Read May Meeting, 1917.) 



The attention of the writer was directed some years ago to the 

 possibility that imbibition pressure exerted outwardly on the inner 

 surface of the cell wall by the protoplast might quantitatively largely 

 overshadow osmotic pressure as a factor in growth^. It was at any 

 rate clear that the bursting of certain kinds of cells (tannin-idioplasts, 

 raphide-cells, etc.), upon being placed in solutions of crystalloids, 

 glycerol, etc. of higher concentrations than those of the cells them- 

 selves, could not be due to osmotic pressure, but to the imbibition 

 of water by an emulsoid. In the instance of the tannin-idioplast, this 

 emulsoid has been identified^ as a cellulose-like mucilage capable of 

 coagulation. The mucilages found very generally, if not indeed 

 universally, in the vacuoles of living cells, and those which reach their 

 maximum expression in the mucilage idioplastsof cacti, mallows and in 

 cells of identical or similar morphology in many other plants (e.g. Tilia), 

 must exert more or less imbibition pressure, according to the state of 

 hydratation and the nature of the solutes present. The total out- 

 wardly directed pressure playing against the cell wall must therefore 

 be the summation effect of osmotic pressure and that of imbibition. It 

 need hardly be added that when the mucilages are highly dispersed, the 

 imbibition pressure will be_ correspondingly low, and osmotic pressure 

 may be the dominant factor. To what extent a high concentration of 

 an emulsoid within the vacuole may become dominant we are yet 

 unable to say, though it is clear that the rôle played by such bodies 

 can by no means be disregarded.^ 



■ In this connection it may be pointed out that idioplasts which 

 contain high mucilage or other emulsoid concentrations are conspicuous 

 for their great size as compared with the cells which surround them 



'Research assisted by a subvention from the Cooper Fund for Medical Re- 

 search, McGill University. 



-Lloyd, F. E. The behaviour of tannin in persimmons. Plant World 14: 1-14, 

 1911. 



•'Clark, E. D. Notes on the chemical nature of the tannin-masses of (he per- 

 simmon. Bioch. Bull, 2: 412. 1913. 



^Kunkel, L. O. A Study of the Problem of Water Absorption. Ann. Rep. 

 Mo. Bot. Gard., 1912; MacDougal, D. T. The Mechanism and Conditions of Growth. 

 Mem. N.Y. Hot. Card. 6:5-26. pi. 1, 1916. and papers tlicrcin ciled. 



