148 OF THE STRUCTURAL ELEMENTS OF THE HUMAN BODY. 



The exposition given above explains the grounds upon which Professor Jackson 

 dissents from the opinion of the author, who regards Organic force as identical 

 with the Physical forces. No one can deny their correlation ; but no phenomena 

 of the Physical forces have analogy or resemblance to the persistent maintenance 

 of typical forms amidst the ceaseless commotion of the atoms of organic matter 

 in its eternal circle of decomposition and recombination, the constant phenomena 

 of organic actions. 1 



The same doctrine has also been advanced by Dr. Kirkes in his " Manual 

 of Physiology/' in the elucidation of which, after describing the " formative 

 force" as the "ability manifested in living bodies to form themselves out of 

 materials dissimilar from them/' he employs the following language : 



" The property to which is referred the formative power of living beings is, 

 however, no simple property, such as the ' attraction' of mechanical science or 

 the ' affinity' of chemistry. These manifest themselves in acts so simple and 

 almost uniform, that the hypothesis which assumes the existence of such pro- 

 perties, supplies at once the language in which their laws of action may be 

 enunciated. But in the simplest exercise of living formative power, even in 

 that which accomplishes the formation of a cell, there is evidence of the opera- 

 tion of many forces; mechanical force is shown in the determination of the po- 

 sition, shape, and relations of the cell ; chemical force is the determination of 

 the composition of its walls and contents, and with these, or as if directing them, 

 that vital force, different from them and from all other known physical forces, 

 is in operation, by virtue of which the cell acquires all the properties that charac- 

 terize the species or organ to which it is attached, and becomes capable of taking 

 part in vital processes even in such processes as those in which itself originated. 



" Thus the vital formative force seems not to oppose or exclude, but to include 

 and direct physical forces that issue from the mere matter of the organic body. 

 It may therefore be believed that every vital act is accompanied with physical 

 changes in the active matter ; but there is no sufficient evidence that such 

 changes ever wholly constitute or make up any of those that are called vital acts. 

 In all those acts or processes, some force is exercised peculiar to the state of life, 

 and as different from all recognized physical forces as they are different from one 

 another. We cannot tell how much in each act of the living body is physical, 

 and how much depends on the peculiar vital force. The advancing knowledge 

 of the physical sciences does, indeed, prove every year that effects which used to 

 be ascribed to vital forces are due to the operation of the forces of chemistry 

 and mechanics ; and it may be observed, generally, that the substances in which 

 the processes of organic life are most actively carried on, are those whose chemi- 

 cal composition is most remote from that of inorganic matter. Still many things 

 yet remain, observed only in the living body, so completely dependent on the 

 maintenance of the whole state of life, and so different from what physical 

 forces ever accomplish in dead matter, that we cannot refer them to the opera- 

 tion of those forces. Any hypothesis which would abolish the idea of vital 

 formative force would be much less reasonable and useful than that which ad- 

 mits it ; indeed, unless we admit the existence of such a force in the processes 

 of organic life, and adopt the language which the hypothesis suggests, it is 

 hardly possible to express the ordinary facts of Physiology." 3 Ed.~] 



3. General Survey of the Life of Man. 

 128. It will be advantageous, before proceeding further, to apply the doctrines 



1 Lecture introductory to the course, on the Institutes of Medicine in the University of 

 Pennsylvania, by Samuel Jackson, M. D., Philadelphia, 1851. 



2 Manual of Physiology, by Wm. Senhouse Kirkes, M. D., assisted by James Paget, 

 F. R. S.: Philadelphia, Lea & Blanchard, p. 39, Am. Ed. 



