11)14] on Plant-Autographs and their Revelations 193 



Spontaneous Pulsation. 



In certain animal tissues a very curious phenomenon is observed. 

 In man and other animals there are tissues which beat, as we say, 

 spontaneously, As long as life lasts, so long does the heart continue 

 to pulsate. There is no effect without a cause. How, then, was it 

 that these pulsations became spontaneous ? To this query, no fully 

 satisfactory answer has been forthcoming. We find, however, that 

 similar spontaneous movements are also observable in plant tissues, 

 and by their investigation the secret of automatism in the animal may 

 perhaps be unravelled. 



Physiologists, in order to know the heart of man, play with those 

 of the frog and tortoise. " To know the heart," be it understood, is 

 here meant in a purely physical, and not in a poetic sense. For this 

 it is not always convenient to employ the whole of the frog. The 

 heart is therefore isolated, and made the subject of experiments as to 

 what conditions accelerate, and what retard, the rate and amplitude 

 of its beat. When thus isolated, the heart tends of itself to come to 

 a standstill, but if, by means of a fine tubing, it be subjected to 

 internal hydrostatic pressure, its beating will be resumed, and will 

 continue uninterrupted for a long time. By the influence of warmth, 

 the frequency of the pulsation may be increased, but its amplitude 

 diminished. Exactly the reverse is the effect of cold. The natural 

 rhythm and the amplitude of the pulse undergo, again, appropriate 

 changes under the action of different drugs. Under ether the heart 

 may come to a standstill, but on blowing this off the beat is renewed. 

 The action of chloroform is more dangerous, any excess in the dose 

 inducing permanent arrest. Besides these there are poisons also 

 which arrest the heart-beat, and a very noticeable fact in this con- 

 nexion is, that some stop it in a contracted, and others in a relaxed 

 condition. Knowing these opposed effects, it is sometimes possible 

 to counteract the effect of one poison by administering another. 



Rhythmic Pulsations in Desmodium. 



The existence of such spontaneous movements is seen in the well- 

 known Indian plant, Desmodium gyrans, or the telegraph-plant, 

 whose leaflets dance up down more or less continuously. The 

 characteristics of the automatic pulsations in the plant could not be 

 determined on account of the apparent impossibility of obtaining a 

 record. The leaflets are too minute and the pull exerted too feeble to 

 overcome friction of the recording surface. This difficulty I have 

 been able to remove by the device of my Oscillating Eecorder. From 

 the records thus obtained, I am enabled to say that the automatic 



Vol. XXI. (Xo. 108) o 



