436 THE CANADIAN NATURALIST. [I)eC. 



36 On this question of vital force, see Liebig, Animal Cbemistiy. 

 " The increase of mass in a plant is determined by the occurrence of a 

 decomposition which takes place in certain parts of the plant under the 

 influence of light and heat." 



"The modern science of Physiology has left the track of Aristotle. 

 To the eternal advantage of science, and to the benefit of mankind it no 

 longer invents a horror vaciii, a qiiinta essentia, in order to furnish 

 credulous hearers with solutions and explanations of phenomena, whose 

 true connection with others, whose ultimate cause is still unknown." 



" All the parts of the animal body are produced from a peculiar fluid 

 circulating in its organism, by virtue of an influence residing in every 

 cell, in every organ, or part of an organ." 



" Physiology has sufficiently decisive grounds for the opinion that 

 every motion, every manifestation of force, is the result of a transforma- 

 tion of the structure or of its substance ; that every 'conception, every 

 mental afi'ection, is followed by changes in the chemical nature of the 

 secreted fluids ; that every thought, every sensation is accompanied by 

 a change in the composition of the substance of the brain." 



" All vital activity arises from the mutual action of the oxygen of the 

 atmosphere and the elements of food." 



" As, in the closed galvanic circuit, in consequence of certain changes 

 which an inorganic body, a metal, undergoes, when placed in contact 

 with an acid, a certain something becomes cognizable by our senses, 

 which we call a current of electricity ; so in the animal body, in con- 

 sequence of transformations and changes undergone by matter previously 

 constituting a part of the organism, certain phenonamena of motion and 

 activity are perceived, and these we call life or vitality." 



" In the animal body we recognise as the ultimate cause of all force 

 only one cause, the chemical action which the elements of the food and 

 the oxygen of the air mutually exercise on each other. The only known 

 ultimate cause of vital force, either in animals or in plants^ is a chemical 

 process." 



" If we consider the force which determines the vital phenomena as a 

 property of certain substances, this view leads of itself to a new and more 

 rigorous consideration of certain singular phenomena, which these very 

 substances exhibit; in circumstances in which they no longer make a 

 part of living organisms." 



Also Owen, Eichard, (Derivative Hypothesis of Life and Species, 

 forming the 40th chapter of his Anatomy of Vertebrates, republished in 

 Am. J. Sci. II, xlvii, 33, Jan. 1869.) In the endeavour to clearly compre- 

 hend and explain the functions of the combination of forces called 

 ' brain,' the physiologist is hindered and troubled by the views of the 

 nature of those cerebral forces which the needs of dogmatic theology 

 have imposed on maakind." * " '' Religion pure and undefiled, can 

 best answer how far it is righteous or just to charge a neighbour with 

 being unsound in his principles who holds the term ' life ' to be a sound 

 expressing the sum of living phenomena ; and who maintains these 

 phenomena to be modes of force into which other forms of force have 

 passed; from potential to active states, and reciprocally; through the 



