THE SCOPE OF BIOLOGY. 99 



actions in the environment) consists of two quite distinct por- 

 tions. Objective Psychology deals with those functions of the 

 nervo-muscular apparatus by which such organisms as possess 

 it, are enabled to adjust inner to outer relations ; and includes 

 also, the study of the same functions as externally manifested 

 in conduct. Subjective Psychology deals with the sensations, 

 perceptions, ideas, emotions, and volitions that are the direct 

 or indirect concomitants of this visible adjustment of inner 

 to outer relations — considers these several kinds of conscious- 

 ness in their genesis, and their connexions of co-existence and 

 succession. Consciousness under its different modes and 

 forms, being a subject-matter radically distinct in nature from 

 the subject-matter of Biology in general ; and the method of 

 self-analysis, by which alone the laws of dependence among 

 changes of consciousness can be found, being a method un- 

 paralleled by anything in the rest of Biology ; we are 

 obliged to regard Subjective Psychology as a separate study 

 — not absolutely, of course, but relatively to the mind of each 

 student. And since it would be verj' inconvenient to dis- 

 sociate Objective Psychology from Subjective Psychology, 

 we are practically compelled to deal with the two as forming 

 an independent sub-science, to be treated apart from the lower 

 divisions of Biology. 



Obviously, the functional phenomena presented in succes- 

 sions of organisms, similarly divide into physiological and 

 psychological. Under the physiological, come the 



modifications of bodily actions that arise in the course of 

 generations, as concomitants of structural modifications ; and 

 these may be modifications, qualitative or quantitative, in 

 the molecular changes classed as chemical, or in the organic 

 actions classed as physical, or in both. Under the 



psychological, come the qualitative and quantitative modifica- 

 tions of instincts, feelings, conceptions, and mental changes 

 in general, that occur in creatures having more or less 

 intelligence, when certain of their conditions are changed. 

 This, like the preceding department of Psychology, has in 



