29 



iStk January, 1881. 



The President, Professor Purser, in the Chair. 



A Paper was read by Thomas H. Corry, Esq., M.A., M.R.I. A., 

 F.Z.S., on 



THE MOVEMENTS OF FLUIDS IN PLANTS. 



The subject which will engage our attention this evening is 

 perhaps the most important in the whole science of Vegetable 

 Physiology, and though it has received attention from investi- 

 gators for nearly two centuries, it appears even yet, so far as the 

 present state of our knowledge extends, impossible to give 

 an adequate, definite, and deductive account of the modus 

 operandi of these movements in detail. Certain of the facts, 

 however, are well known and established by experiment, while 

 over others hangs a shadow of uncertainty, since we are 

 compelled to draw our conclusions as to the internal pro- 

 cesses, on all essential points, from a careful study of the external 

 phenomena in the plants themselves ; for the forces acting in 

 the living plant act under conditions which are widely different 

 from those which obtain in the ordinary apparatus of the 

 laboratory. 



I will begin by describing the structure of one of the 

 simplest plants, viz., Pandorina. It consists only of a single 

 mass of living tissue, which we call protoplasm, surrounded by 

 a clear, glassy, transparent envelope or wall, termed the cell- 

 wall, for we designate the lump of living protoplasmic material 

 as a cell, and speak of this plant as being unicellular. This 

 envelope is not of universal occurrence in plants, for certain 

 plants, during either the whole or a portion of their existence, 



