220 GEOLOGICAL BIOLOGY. 



the history. The reason why the course of development has 

 been what it is may be no more evident than the reason why 

 gold is yellow and heavier than sulphur ; in a particular case 

 the sufficient reason is that it is like that of its ancestors. 



Beginning of Individual Life and Development. In a previ- 

 ous chapter the stages of development of the individual are- 

 described. It is there shown how the simple cell is without 

 distinction of parts, other than as protoplasm with cell-walls ; 

 a cell-nucleus, which is of great importance, and regarding 

 which recent investigations with high power of the microscope 

 are bringing out wonderful characters and functions ; and a 

 vacuole, often present, but the function of which is unknown. 

 From such a cell the individual grows to the state of a com- 

 plex, independent organism, such as the living Vertebrate,, 

 seen in its highest representative, Man. 



Hypotheses regarding the Phylogenetic Evolution of Races. 

 The term Ontogeny has been applied to this development, 

 and to distinguish it therefrom, Phytogeny, or race-develop- 

 ment, has been proposed to indicate the analogous passage 

 from the simplest undifferentiated Protozoan, the Amoeba, or 

 Monera, through the several stages of increasing complexity 

 of organization to the most highly differentiated Vertebrate. 

 Many attempts have been made to construct the history of 

 the whole organic world on this basis, i.e., to construct 

 phylogenetic trees of the ancestors of beings now living on the 

 earth. Haeckel's " History of Creation " is one of the earlier 

 and most elaborate, and perhaps most artificial, of such 

 treatises; for as science has developed, our knowledge of the 

 true genetic relationship in some particular lines of organisms 

 has greatly increased. When Haeckel's work was published 

 (1868), the new methods of investigation, so greatly stimu- 

 lated by the appearance of Darwin's " Origin of Species," 

 had only begun to affect the students of fossil remains ; and 

 it is mainly since that date that the classification of organisms 

 has been revised on the basis of genetic affinities determined 

 by comparative studies of structure. 



The analysis of organic structure, from the phylogenetic 

 point of view, is very instructive and suggestive if it be not 

 overdone, It helps us to attain general notions of organiza- 



