IN THE MuTOR organs of leaves 



o 



of the higher animals, dependent as 



tluy are on supplies of concentrated nutritive 

 materials, such means are essential. The end to be attained in both ca>es is a due supply 

 of nutritive material to make good the constant waste to which living protoplasm it 

 subject in the exercise of its functional properties; in the ono case this has been attained 



by great specialisation of assimilatory function and 



great 



of surface, in 



the other by great specialisation of contractile and irritablo function. Even the most 

 indifferent protoplasm possesses a certain amount of contractile function; but in tracing 

 the course of evolution along the animal and vegetal series of organisms wo find that, 

 whilst in the former this has become more and more highly specialised, in the latter it 

 has remained in relative abeyance, while assimilatory power has become predominant; so 

 that it would bo just as surprising and anomalous to find any of the higher plants 

 exhibiting phenomena implying the presence 



as to find any of the higher animals capable of supplying their nutritional requirements 

 from purely inorganic sources. 



Both on a priori grounds and in the light of abundant positive evidence there is 

 thus good reason to believe that massive movements in the higher plants are not related 

 to the exercise of contractile function, but to assimilatory function as affecting the 



of highly specialised contractile apparatus 



osmotic properties 



local supply and loss of fluid. 



of the tissues, or to purely physical causes influencing general 



or 



CHAPTER II 



a* bistingttishtb from simple saturation. 



It is not difficult to adduce evidence showing that turgescence is distinct from mere 

 saturation of tissues; but perhaps the most striking proof is that which is afforded by 

 the phenomena presenting themselves in connection with the exposure of many succulent 

 tissues to the action of anaesthetics. The demonstration is peculiarly striking in such 



which the turgescence of the tissue depends are unstable 

 in constitution and are not accumulated in any considerable amount; so that any depres- 

 sion of the functional activities to which they owe their origin is at once followed by 

 a discharge of fluid from the cells; and because, as Dubois has pointed out,* the area of 

 the intercellular spaces is too small to accommodate the masses of it which escape, so 

 that free exudation takes place upon the surface through the stomatic orifices. The follow- 

 ing experiments illustrate the nature of the phenomena presenting themselves in the case 

 of various common succulents : 



cases, because the materials on 



A.— Kalanchoe laciniata. 



Experiment I. — A leaf weighing 6*54 grammes was set in a chloroform-chamber at 



10-9 A.M. 



A certain degree of darkening in its colour and visible exudation of minute 



drops of fluid upon the surface were recognisable at 10-17 



The 



dation advanced 



rapidly, and at 12-30 p.m. the leaf had become somewhat flaccid and had acquired 



* « 



canisme de Faction de Anesth^Biques." Dr. R. Dubois, Eevue G^ndralc 



September 





