STIMULI AND THEIR ACTIONS 375 



raents cease, and, moreover, after some time it is no longer possible 

 to call forth by stimuli the well-known movements, which consist 

 of a falling of the branches and a folding together of the leaves. 

 The irritability is extinguished, the plant is in narcosis. " What a 

 singular thing," says Claude Bernard, " plants can be anaesthetised 

 like animals, and absolutely the same phenomena can be observed 

 in the two." 



Like the turgescence-movements,the growth-movements of plants 

 also cease in narcosis, and the secretory movements of the Biatomem, 

 Oscillarioe, and Besmidiacew ^ are wanting. 



Contraction-movements are also depressed by narcotics ; but, 

 as a rule, at the beginning of the influence a short stage of excitation 

 is noticed, in which the movements are accelerated. The 

 protoplasmic movements of Amceba cease after the cells have con- 

 tracted into a ball. As Binz ('67) found, quinine especially exerts 

 a powerful paralysing action upon the amoeboid movements of 

 leucocytes. Engelmann ('68) carried out extensive investiga- 

 tions upon the depressing action of narcotics upon ciliary motion. 

 When he let the vapour of ether or chloroform act upon the ciliated 

 cells of the pharyngeal mucous membrane of a frog in a gas-chamber, 

 after a rapid preliminary stage of excitation, in which the motion 

 was accelerated, a standstill of the cilia took place. If the duration 

 of the action was not too long, the motion appeared again after the 

 introduction of fresh air. According to the observations of the 

 Hertwigs ('87), similar behaviour was exhibited by the flagella of 

 spermatozoa that had been brought to complete standstill by ether- 

 and chloroform-vapours, as well as by small doses of quinine and 

 chloral hydrate, so that the fertilisation of the ovum was hindered 

 by the absence of their movements. In Infusoria also by the intro- 

 duction of chloroform-water, after a short stage of excitation in 

 which the cells whirl madly through the water, ciliary motion is 

 inhibited. In Stentor, in addition to this fact, the paralysis of 

 the myoids by the chloroform-water can be observed at the same 

 time. In their undisturbed condition the Stentors are extended in 

 the form of delicate trumpets with their aboral pole attached at the 

 bottom (Fig. 168, A). From time to time, partly spontaneously 

 and partly as a result of stimulation, they jerk together into 

 stalked balls (Fig. 168, G) by the contraction of their fine myoid-fibres 

 that extend from the upper to the lower end of the cell-body in the 

 exoplasm. In narcosis, however, after a sudden twitch at the begin- 

 ning of the influence, they assume a stage of moderate contraction 

 (Fig. 168, B), their cilia cease to beat, and their bodies do not shrink 

 into the customary ball either spontaneously or upon stimulation, 

 until by transference into fresh water the narcosis is ended. Like 

 the smooth myoid-fibres, the irritability of cross-striated skeletal 

 muscles also is completely abolished by narcosis. A frog's muscle 



1 Cf. p. 231. 



