On the Causation of Vital Movement. 



427 



Ckooxiax Lecture. — "On the Origin and the Causation of 

 Vital Movement (Ueber die Entstehung der vitalen Bewegung)" 

 By Dr. W. KuHNEj Professor of Physiology in the University 

 of Heidelberg. Communicated by Professor M. FOSTER, 

 Sec. K.S. Received April 22, Delivered in the Theatre of 

 the Royal Institution May 28, Revised August 15, 1888. 



(Translation.) 



Among the phenomena of life the movement of masses, or mechanical 

 work, takes a prominent place. It is the most accessible of all the 

 vital processes to our sensual perceptions, so universally distributed, 

 and so bound up with most of the activities of organisms, that it 

 might almost be designated the incarnation of life. 



In saying this it must be understood that vital movement is by no 

 means exclusively confined to animals, that it is not, as was once 

 believed, a special animal function ; on the contrary it is an attribute of 

 all living matter, as well of the lowest creatures as of the most highly 

 developed plants, so that, however extraordinary it may appear, the 

 activity of our muscles which enables us to transform sensation into 

 action finds an analogue in the plant. Our conviction of the inter- 

 connexion and profound unity of all living things has thus a physio- 

 logical foundation, based as it is not merely on the community of 

 derivation and of structure of living things, but also on the proof of 

 similar activities. 



If a division of the morphological from the physiological is in any 

 way permissible, it may be said that the unitary conception of life 

 for which our age is distinguished rests in a higher degree on the 

 knowledge of vital processes than is commonly recognised, and in fact 

 is just as much founded on physiological experience as on that of the 

 forms of the organism. 



From the traditional conception of life, which scarcely contained 

 more than that everything between life and death is the antithesis of 

 the not living, it is a long road we have had to travel to attain to the 

 modern conception of the reed unity of life ; and a remarkable road, 

 since it bears witness to the confident anticipation of victory, in face 

 of all impediments raised up by science itself. Movement, and nothing 

 less, had been placed at the summit of that antithesis, which physico- 

 chemical research in the animal and vegetable kingdom had revived 

 with the discovery that the plant transformed kinetic into potential 

 energy, and the animal the latter into the former. While the animal 

 made use of oxygen to generate heat and perform work through the 

 metabolism of its substance, the plant made use of the heat in reducing 



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