xii CONTENTS. 



Pages 

 Romanes's conception of the psychic activity of Proto- 



organisms 105 



Irritability and cellular psychology 107-1 10 



Correspondence between Ch. Richet and Alfred Binet, ap- 

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

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



APPENDIX. 



Additional cuts illustrative of : 



The Conjugation of the Paramtecium aurelia 1 16 



The Conjugation of the S lent or ccertileus 116 



The Copulation of the Stylonichia mytilus 116 



The Conjugation of the Car chesium poly pimtm 117 



The Conjugation of the Chilodon cucullulus (with explana- 

 tions) 1 18 



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



