1-3 1 



aumaauM on fluctuation in tusgescecce. 



of chloroform under circumstances favouring 



III -Exposure to the influence of the vapour 01 «"-— ~-» ™ 1 ^ 



Ll transpiratory removal of water from the tissues constantly occasions rapid 

 movements in pinnules, but only exceptionally induces rapid movements of primary 



TV -Neither exposure to a desiccated atmosphere, naless the aridity be very extreme, nor 



exposure to a humid atmosphere containing the vapour of chloroform is capable 

 of inducing rapid, sudden movements ; but exposure to a desiccated atmosphere 

 containing °the vapour of chloroform is constantly attended by occurrence of such 



» 



movements. 

 V.-Tke effects following exposure to the influence of the vapour of chloroform, even in cases 



where the treatment has been pushed so far as to cause actual death, are purely 

 localised to those areas of a plant which are directly exposed to the vapour; and 

 the death of comparatively large areas in an axis resulting from prolonged exposure 

 neither affects the conduction of water by the water-conducting system, nor interferes 

 with the propagation of the conditions which give rise to the occurrence of movements. 



These facts are quite inexplicable on any theory which ascribes the 



of 



of the leaves to stimulation and active contraction of the protoplasts of the motor organs. We 



ground for belie 



to antesthetic vapours leads to stimulation of protoplasmic 



activity of any kind, but we have distinct evidence that it acts in precisely opposite fashion. "Were 

 the movements dependent on stimulation of contractile protoplasts in the motor organs by the 

 antosthetio vapour, thoy ought to retain the same character, no matter what the hygrometrio properties 

 of the atmosphere be; whereas as a fact sudden rapid movements never occur so loug as the atmosphere 

 is humid, and constantly manifest themselves when it is desiccated, although similar atmospheric 

 ariiity alone is incapable of inducing them, or indeed of inducing any movements whatever. More- 

 over, were the movements dependent on protoplasmic stimulation and active contraction, the fact that 

 rapid pinnular movements are phenomena of normal occurrence on exposure to a desicoated atmosphere 



contaiuing vapour of chloroform, whilst rapid petiolar movements are absolutely exceptional, would remain 

 a hopeless mystery. 



But on the theory that the movements are dependent on losses in turgesoence in the tissues of 



the muter organs connected, not with any active protoplasmic contraction, but either with decrease 

 in the osmotic capacity of the cell-sap, or with influences facilitating local filtration within the 

 tissues of the motor organs, or disturbing pre-existent relations of equilibrium between general supply 

 aud loss of water, all the phenomena become readily explicable. Where plants or portions of plants 

 are exposed to the influence of the vapour of chloroform in a saturated or practically saturated 

 atmosphere (as in the case of experiments Y, VI, aud X) pinnular movements occur; but they are of the 

 Slow insensibly progressive character normally present in cases where diminutions in turgesoence 

 occur m connection with decrease or removal of normal stimulation. They are of the same character 

 as those occurring periodically in connection with the diminution and cessation of solar stimulation 

 at sundown They are evidently dependent solely on the gradual loss of osmotic capacity in the 



tissues of the motor organs attending the depression of assimilatory activity caused by the action 

 of the anaesthetic. Tin ' * * ■ J J 



Where (as in experiment VII) conditions 



greater the rate of movement increases, because here the escape of liquid from the interior of the 



cells of the motor organs accompanying depression of protoplasmic functional activity is facilitated by 

 continuous evaporative loss from the tissues generally. Where 



VIII. IX 



W ™i«f,v.„ . a -j « n mth ex P° sure to a desiccated atmosphere, conditions providing 



diRtriWtti »U,^ *u„ ,-.*.__ , appearance. Such movements are not, however, evenly 



««t»uuwu mrougnout tne different parts of the leaves Th a . „ ..,••/ •* 



equally in the primary petiol, aad n J ™ u so f 3 "*** " 0B " t "? 7 m ^ *""? <*> ^ 



Are we to suppose that the vapour o ohloroZn 1„ * "? ^^^ S ™' " * ^"^ 



stimuWt to the protoplasts of the ter^ ^T w h , it Z f T"T -«"»\- » ' 



primary palviui aud has no «JZ It Zle I tuT 7 1 " T^ 1 T' t 



wuaiever on those of tae seoondary ones? It is surely 





