LIFE IN ITS LOWER AND HIGHER FORMS 35 



tributes to the new life encompassed within the egg. 

 The fertilised egg passes through its earlier stages of 

 development in the embryonic state. 



From these outlines of the history of life in its 

 earlier stages, we must pass rapidly towards the more 

 familiar stages of life subsequent to birth, specially to 

 the sensory and motor activity belonging to animal 

 life. Thereafter, we shall advance to the characteristics 

 of intellectual life belonging to the higher orders of 

 mammalia. We seek, as early as may be, in course of 

 this investigation, to deal with marked differences 

 appearing in organic life, leading onwards to the 

 history of variations, and to the problem of origin 

 of species. 



On whatever phase of organic life attention is turned, 

 structure must account for its activity. All organ 

 ism includes apparatus fulfilling definite functions. 

 With progress in development, we distinguish muscle, 

 nerves, and nerve centres. The amount of force oper 

 ating in development, must in any case be measurable. 

 Diversities of capacity and of faculty come into view. 

 From reference to these, discrimination of species arises 

 In process of these comparisons, a steadily advancing 

 complexity is manifest in the ascending scale of life. 

 When new characters become persistent in a group 

 of individuals, and there is loss of the intermediate 

 forms, then we speak of new species. 1 Here we move 

 into the field of special inquiry regarding relation 

 of species, and man s place in Nature. Successive 

 stages of differentiation in organic structure are ob 

 served. How do new forms of structure arise ? This 

 is the inquiry which has engrossed the attention of 



1 Organic Evolution, Eimer, Cunningham s translation, p. 23. 



