514 REPORT — 1880. 



into the various tissues and secretions, and to tlieir subsequent metamorphosis into 

 lifeless compounds. 



After this lapse of time, it will certainly be granted that, quite irrespectively of 

 the admissibility or otherwise of the particular illustrations adduced, or of .the 

 truth or error of any of the conclusions drawn — and some at least are so true that 

 they seem to iis now all hut truisms, and you may be disposed to ask me why I 

 should tell you over again a story so often told before — there is no doubt that 

 Liebig's manner of treating the subject did exert an immense influence, by stimu- 

 lating investigation, by fixing attention on tbe points to be investigated, and on 

 the methods that must be followed, and thus, by leading to the establishment or 

 the correction of any special views he put forward, and to a vast extension of our 

 knowledge on the complicated questions involved. 



In the third part of Liebig's second volume he treats of the phenomena of 

 motion in the animal organism. It is to his views in regard to one aspect only of 

 this very wide and very complicated subject that I propose to call your attention 

 here, as it is chiefly in so far as that aspect is concerned that the question is of 

 interest from the point of view of the agricultural chemist. He says :— 



' We observe in animals that the conversion of food into blood, and the contact 

 of the blood with the living tissues, are determined by a mechanical force, whose 

 manifestation proceeds from distinct organs, and is effected by a distinct system of 

 organs, possessing the property of commuuicatiug and extending the motion which 

 they receive. We find the power of the animal to change its place and to produce 

 mechanical efiects by means of its limbs dependent on a second similar system of 

 organs or apparatus.' 



He points out that the motion of the animal fluids proceeds from distinct 

 organs (as, for example, that of the blood from the heart), which do not generate 

 the force in themselves, but receive it from other parts by means of the nerves ; the 

 limbs also receive their moving force in the same way. He adds : ' Where nerves 

 are not found, motion does not occur.' Again : — 



* As an immediate effect of the manifestation of mechanical force, we see that a 

 part of the muscular substance loses its vital properties, its character of life ; that 

 this portion separates from the living part, and loses its capacity of growth and its 

 power of resistance. We find that this change of properties is accompanied by 

 the entrance of a foreign body (oxygen) into the composition of the muscular 

 fibre. . . ; and all experience proves that this conversion of living muscidar fibre into 

 compounds destitute of vitality is accelerated or retarded according to the amount 

 of force employed to produce motion.' He adds that a rapid transformation of 

 muscidar fibre determines a greater amount of mechanical force, and that conversely 

 a greater amount of mechanical motion determines a more rapid change of matter. 



' The change of matter, the manifestation of mechanical force, and the absorp- 

 tion of oxygen, are, in the animal body, so closely connected with each other that 

 we may consider the amount of motion and the quantity of living tissue transformed 

 as proportional to the quantity of oxygen inspired and consumed in a given time 

 by the animal.' Again: — 



' The production of heat and the change of matter are closely related to each 

 other ; but although heat can be produced in the body without any change of 

 matter in living tissues, yet tbe change of matter cannot be supposed to take place 

 without the co-operation of oxygen.' 



Further, on the same point : — ' The sum of force available for mechanical pur- 

 poses must be equal to the sum of the vital forces of all tissues adapted to the 

 change of matter. If, in equal times, unequal quantities of oxygen are consumed, 

 the residt is obvious in an unequal amount of heat liberated, and of mechanical 

 force. When unequal amounts of mechanical force are expended, this determines 

 the absorption of corresponding and imequal quantities of oxygen.' 



Then, more definitely still, referring to the changes which take place coincidently 

 with the exercise of force, and to the demands of the system for repair accordingly, 

 he says : — 



* The amount of azotised food necessary to restore the equilibrium between waste 

 and supply is directly proportional to the amount of tissues metamorphosed. The 



