176 GEOLOGICAL BIOLOGY. 



the heterogeneous chemicals uniting to form a homogeneous 

 compound. The final result of chemical action is the com- 

 pound with homogeneous properties throughout, theoretically 

 and historically composed of sundry elements, but effectively 

 simple, uniform and homogeneous. So, too, in crystallization 

 the tendency is, in the heterogeneous solution, for the like 

 things to associate according to regular arrangement of parti- 

 cles ; from heterogeneity of arrangement the law is toward 

 simplicity and regularity of form. 



The Attainment of Heterogeneity. — When these two modes of 

 activity come into conflict the organism expresses its vitality, 

 we say, by overcoming the disintegrating chemical and physi- 

 cal forces about it. The intrinsic tendency of oi-ganisni is, then, 

 to attain heterogeneity, or dissimilarity of kind, dissimilarity 

 of form, morphologically , and dissimilarity of function, 

 physiologically. This we see in the development ot the 

 cell, in the construction of tissues and of organs, in the 

 growth of the individual, or technically, in all the stages of 

 ojitogenesis. 



Grand Results of Ontogenesis, or Development of the Individual. 

 — This is not the place to discuss the details of ontogenesis, — 

 in the departments of Histology, Physiology, Zoology, and 

 Botany these details are fully elaborated ; but it is important 

 to note what are the general results involved, or the history of 

 the stages by which the individual attains its distinguishing 

 characters. The first analysis of the organism shows us that 

 the two primary characteristics of organism are form and 

 growth, and, in describing any individual organism, to be com- 

 plete, our description must include an account of both the 

 morphological and the physiological characters. From the 

 earliest life of the cell this development is a process of divi- 

 sion — division of substance or differentiation, division ot 

 action or function, i.e., speciali::ation. The great complexity 

 of the higher organism is accomplished, not by addition and 

 aggregation of new particles from outside, but it is a work of 

 the cells from within, taking in crude physical matter, assimi- 

 lating and reconstructing it, and then, by subdivision de- 

 veloping the general structure. In the higher organism the 

 result of this elaboration is seen in a ereat elaboration of 



