ORGANIC ELEMENTS 15 



up, and in the interstices of which lodge the contained 

 lymph and lymphoid fluids, or it is the decidedly solid 

 material which imparts to the human and other bodies 

 that character of enduringness and individuality which 

 gives them their living generic features. 



Its chemical and physiological characteristics are to some 

 extent absolutely definite, while its power to assume what- 

 ever degree of consistence is necessary for specific purposes 

 is unbounded, or limited only by the organic requirements 

 of the particular organism. Every feature, organ, and 

 histological development marks its power of adaptation, 

 and the universality of its use in every local variety of 

 circumstance, temporary and permanent, which arises 

 during developmental and evolutional progress ; while 

 the process of nutrition but marks the everyday work 

 which it is accomplishing in the economy of growth and 

 decay, of substitution of new for old, and of the main- 

 tenance of tissue integrity and systemic health. All the 

 tissue elements are thus the result of the disposition of 

 protoplasm on definite formative lines, during the long 

 developmental progress of embryonal, foetal, infantile, 

 adolescent, and senile life, and each stage of that life is 



o 



marked by a departure from the other, in obedience to 

 the effects of environment on the details of its incidence, 

 and the intensity of its local and general involvement of 

 these tissue elements. While these departures are deter- 

 mined by unfailing law, when the conditions of life are 

 absolutely perfect, and manifest themselves in regular and 

 unfailing order in consequence, it is equally certain that 

 any departure from these conditions must be followed by 

 a departure from that order, in proportion to the amount 

 of the disturbing causes and the directions in which they 

 operate. 



The protoplasmic elements of all tissues are surrounded 

 and inter-penetrated by a fluid medium, different in 

 chemical composition from them, and wanting in the 

 property of life, but nevertheless essential for the mani- 

 festation of vital properties on the part of the protoplasmic 

 elements contained therein, and necessary for the passage 

 of dynamic influence from cell to cell, from tissue to tissue, 

 and from the external world to the sentient structures and 



