xii CONTENTS. 



Pages 

 Romanes's conception of the psychic activity of Proto- 



organisms 105 



Irritability and cellular psychology 107-110 



Correspondence between Ch. Richet and Alfred Binet, ap- 

 pearing in the Revue Phitosofhique of February, 1888, re- 

 printed from THE OPEN COURT of December 27, 1888.110-115 



APPENDIX. 



Additional cuts illustrative of : 



The Conjugation of the Paramacium aurelia 116 



The Conjugation of the Slentor ccerulfus 116 



The Copulation of the Stylonithia mytilus 1 16 



The Conjugation of the Carchesium polypinum 117 



The Conjugation of the Chilodon cucul lulus (with explana- 

 tions) 118 



Addenda. Notes and References omitted in the text. . 121 



