PRELIMINARY ENQUIRIES. 



CHAPTER I. 



MENTAL PHENOMENA IN ACEPHALOUS ANIMALS. 



THE student of comparative psychology cannot too soon di- 

 vest himself of the erroneous popular idea that brain and 

 mind are in a sense synonymous ; that brain is the sole organ 

 of the mind ; that mind cannot exist without brain ; or that 

 there is any necessary relation between the size, form, or 

 weight of the brain and the degree of mental development. 

 Even in man there is no necessary relation between the size, 

 form, or weight of the brain and the degree of mental deve- 

 lopment ; while the phenomena of disease in him show to 

 what extent lesions of cerebral substance occur without 

 materially affecting the mental life. 



Physiologists are gradually adopting or forming a more 

 and more comprehensive conception of mind, and are coming 

 to regard it as a function or attribute not of any particular 

 organ or part of the body, but of the body as a whole. Long 

 ago the illustrious Milton, discoursing of mind and its seat, 

 properly described the human mind as an attribute of man's 

 body as a whole. In various forms or words this view has 

 been expressed in recent times by Miiller, Lewes, Laycock, 

 Bushnan, Bastian, Maudsley, Carpenter, and others. Ac- 

 cording to these authors the seat of mind is throughout 

 the body (Miiller) ; mind pervades the body (Laycock and 



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