x CONTENTS. 



Pages 



Volvox. Difference between a pluricellular organism and 

 a colony of unicellular organisms. Voluntary combina- 

 tions. The Bodo caudatus 55~6i 



v. 

 THE PSYCHOLOGY OF PROTO-ORGANISMS. 



Remarks upon the psychology of Micro-organisms. Their 

 various actions are direct responses to stimuli from the out- 

 ward world. Perception of external bodies. Choice. 

 Calculation of the positions occupied by external bodies. 

 Movements of Micro-organisms 61-65 



VI. 

 FECUNDATION. 



Fecundation among Infusoria. Historical. Psychological 

 preliminaries of fecundation Observations of M. Bal- 

 biani upon the Paramaecia, the Spirostomes, and the Sten- 

 tors. Copulation. Fecundation among the Vorticels. 

 Observation of Engelmann. Material phenomena in fec- 

 undation. The role of the nucleus, and the role of the 

 nucleolus. Description of the phenomena as seen in the 

 Chilodon cucullulus (see appendix), the Paranuzciiim bursa- 

 ria and in the Param&ciutn aurelia. Observation of M. 

 Balbiani upon Paramaecia, of which the nucleus is overrun 

 with parasites 65-75 



VII. 



FECUNDATION IN HIGHER ANIMALS AND PLANTS. 

 Fecundation in higher animals and plants. The spermato- 

 zoid and the ovule can be compared to Micro-organisms. 

 The elements can live for a certain time independent of 

 the animals from which they come. Their motor organs. 

 The 'movements of the spermatozoid towards the ovule. 

 Length of road to be traveled. Obstacles to be over- 

 come. Windings and intricacies of the path. The sper- 

 matozoid of the silk- worm. Arrival of the spermatozoid in 

 contact with the ovule. Observation of Fol upon the 

 fecundation of the star-fish. The cone of attraction. 



