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RESEARCHES 



ON . 



THE MOTION OF THE JUICES 

 IN THE ANIMAL BODY. 



BY JUSTUS LIEBIG, M.D., 



PROFESSOR OP CHEMISTRY IN THE UNIVERSITY OP GIE8SEN ; 

 EDITED FEOM THE AUTHOR'S MANUSCRIPT, BY 



WILLIAM GREGORY, M.D., 



PROFESSOR OF CHEMISTRY IN THE UNIVERSITY OF EDINBURGH. 



PREFACE. 



The present little work contains a series of experiments, the object of which is to ascertain 

 the law according to which the mixture of two liquids, separated by a membrane, takes place. 

 The reader will, I trust, perceive in these researches an effort to attain, experimentally, to a 

 more exact expression of the conditions under which the apparatus of the circulation acquires all 

 the properties of an apparatus of absorption. 



In the course of this investigation, the more intimate study of the phenomena of Endosmosis 

 impressed on me the conviction that, in the organism of many classes of animals, causes of the 

 motion of the juices were in operation, far more powerful than that to which the name of En- 

 dosmosis has been given. 



The passage of the digested food through the membranes of the intestinal canal, and its 

 entrance into the blood ; the passage of the nutrient fluid outwards from the blood-vessels, and 

 its motion towards the parts where its constituents acquire vital properties, these two funda- 

 mental phenomena of organic life cannot be explained by a simple law of mixture. 



The Experiments described in the following pages will, perhaps, be found to justify the 

 conviction that these organic movements depend on the transpiration and on the atmospheric 

 pressure. 



The importance of the transpiration for the normal vital process has indeed been acknow- 

 ledged by physicians ever since Medicine had an existence ; but the law of the dependence of 

 the state of health on the quality of the atmosphere, on its barometric pressure, and its hygro- 

 nietric condition, has been hitherto but little investigated. 



By the researches contained in my examination of the constituents of the juice of flesh, as 

 well as by those described in the present work, the completion of the second part of my Animal 

 Chemistry has been delayed ; but I did not consider myself justified in continuing that work 

 until I had examined the questions suggested by, and connected withj those researches. 



DR. JUSTUS LIEBIG. 

 GIESSEN, Febniary, 1848. 



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