22 ANIMAL INTELLIGENCE. 



ever, is here full of difficulty, and not the least so on 

 account of the amoeba not only having no nervous 

 system, but no observable organs of any kind ; so that, 

 although we may suppose that the adaptive movements 

 described by Mr. Carter were non-mental, it still remains 

 wonderful that these movements should be exhibited by 

 such apparently unorganised creatures, seeing that as to 

 the remoteness of the end attained, no less than the 

 complex refinement of the stimulus to which their 

 adaptive response was due, the movements in question 

 rival the most elaborate of non-mental adjustments else- 

 where performed by the most highly organised of nervous 

 systems. 



Goelenterata. 



Dr. Eimer attributes ' voluntary action ' to the Medusae, 

 and indeed draws a sharp distinction between what he 

 considers their ' involuntary ' and ' voluntary ' movements. 

 In this distinction, however, I do not at all concur ; for 

 although I am well acquainted with the difiference be- 

 tween the active and slow rhythm upon which the dis- 

 tinction is founded, I see no evidence whatever for 

 supposing that the difiference involves any psychological 

 element. The active swimming is produced by stimu- 

 lation, and is no doubt calculated to lead to the escape of 

 the organism ; but this fact certainly does not carry us 

 beyond the ordinary possibilities of reflex action. And 

 even when, as in some species is constantly the case, 

 bo*its of active swimming appear to arise spontaneously 

 or without observable stimulation, the fact is to be at- 

 tributed to a liberation of overplus ganglionic energy, 

 or to some unobservable stimulation ; it does not justify 

 the supposition of any psychical element being con- 

 cerned.^ 



M'Crady gives an interesting account of a medusa 

 which carries its larvae on the inner sides of its bell- 

 shaped body. The manubrium, or mobile digestive cavity 



* For an account of the natural movements of the Medusae and the 

 effects of stimulation upon them, see Croonian Lecture in P?dl. Tratis. 

 1875, and also Phil Trans. 1877 and 1879. 



