CHAPTER V
PLANT RESPONSE—ON THE EFFECTS OF SINGLE STIMULUS AND OF SUPERPOSED STIMULI

Effect of single stimulus.—In a muscle a single stimulus gives rise to a single twitch which may be recorded either mechanically or electrically. If there is no fatigue, the successive responses to uniform stimuli are exactly similar. Muscle when strongly stimulated often exhibits fatigue, and successive responses therefore become feebler and feebler. In nerves, however, there is practically no fatigue and successive records are alike. Similarly, in plants, we shall find some exhibiting marked fatigue and others very little.

Fig. 16.—Uniform Responses (Radish)

Fig. 17.—Fusion of Effect of Rapidly Succeeding Stimuli

(a) in muscle; (b) in carrot.