PLANT-AUTOGRAPHS—BOSR. 439 
nomenon of nervous impulse in general and the causes operative in 
bringing about the degeneration of the normal function of the nerve. 
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 unraveled. 
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 heartbeat, and a very noticeable fact in this con- 
nection 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 and 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 recorder. From 
