VITALITY 



INTRODUCTION. 



The problem to be here considered is that of vitality. The things we 

 perceive consist of what is physically and chemically designated as 

 "matter." This irrespective of whatever theory may be formed regard- 

 ing the real consistency of what is thus designated. 



In plants and animals this material substance is found to be alive. 

 It manifests the peculiar phenomena that are called vital, and which 

 essentially distinguish living beings from lifeless things. It is, therefore, 

 above all, incumbent upon biologj^ as the science of life, to seek to 

 ascertain the special conditions which give rise to the vital properties of 

 the substance composing plants and animals. 



The explanation of vitality to be here advanced has been arrived at 

 as the result of many years of observation devoted to the vital phenomena 

 of primitive forms of life, such as the Protozoa. 



N"o general definition of life, such as philosophizing biologists have 

 abundantly advanced, can here at all avail. Our insight into the pro- 

 cesses which are operative in the manifestation of vital phenomena, has 

 nowise been furthered by any of these conceptual abstractions. 



But neither, it must be confessed, has biolog}^, despite its minute 

 investigations and diligent endeavors, as yet succeeded in disclosing the 

 true nature of vitality. Guided by the cell-theory and purely me- 

 chanical principles, it has vainl}^ searched for it in the minute structure, 

 the intimate movements, and the chemical constitution of the single 

 cells composing multicellular organisms; and quite especially in the 

 striking occurrences accompanying their mitotic self -division. For, 

 according to the cell-theory, complex organisms are made up of num- 

 berless autonomous vital units or elementary organisms, which multiply 

 by means of self-division. Such complex or multicellular beings have 

 then to be regarded, not as being themselves unitary individuals; but, 

 on the contrary, as being in reality aggregates of elementary units. 



In accordance with the cell-theory, each separate cell, as an autono- 

 mous vital unit, must be the bearer of all that essentially constitutes 

 vitality. Hence the minute investigation of every phase of its vital 

 manifestations, of every visible trace of the changes it undergoes. 



But, however instructive in other respects, it can not be said that the 

 result of all these patient and accurate observations, carried on by a 

 host of competent investigators, has conduced to throw any decisive 

 light on the real nature of vitality. It has failed to show how the sub- 

 stance which composes the cells comes to be actually alive; how it is 

 empowered to maintain its vitality and identity under constant change; 



