22 THE PSYCHIC LIFE 



would suffice to break the feeble bond that unites 

 them. Moreover, their vibratile cilia beat in unison. To 

 explain this concordance in the movements of the two 

 animals, Gruber assumes that the entire mass of their 

 protoplasm performs the function of a diffused nervous 

 system, which has the effect of regulating their move- 

 ments and of making them harmonize. 



We might add that the Infusoria possess not only 

 a diffused nervous system, but that they must of neces- 

 sity possess special nerve centres, endowed with dif- 

 ferent functions. . 



It will be remembered in fact that, under the influ- 

 ence of certain poisonous agents, death is not simultane- 

 ous throughout all parts of the organism. What 

 ceases first are the voluntary movements of the large 

 cilia; the movements of the small cilia are able to per- 

 sist much longer; and finally, when all the cilia have 

 become immobile and rigid, the vesicle has still been 

 seen to pulsate for an hour. This gradual death re- 

 calls what we remark among the Vertebrates; under 

 the influence of poisonous agents, the brain dies first, 

 then follows the spinal cord, and lastly the medulla, 

 which is the ultimum moriens. 



The Organs of Sense. All the Micro-organisms 

 are endowed with sensibility; some, like the Infusoria, 

 have exceedingly sensitive powers. But, hitherto, 

 organs of sense anatomically differentiated have been 

 found in only a very small number of species. Gen- 

 erally, the protoplasmic expansions which we have 

 above described under the name of pseudopodia are 

 regarded as fulfilling the function of rudimentary 

 organs of touch which advise the micro-organism of 

 the presence of objects which happen in its path; but 

 these pseudopodia, which at the same time serve as 



