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 6 voluntary action ? to the Medusae, 
and indeed draws a sharp distinction between what he 
considers their 6 involuntary ? and 6 voluntary ’ movements. 
In this distinction, however, I do not at all concur ; for 
although I am well acquainted with the difference be- 
tween the active and slow rhythm upon which the dis- 
tinction is founded, I see no evidence whatever for 
supposing that the difference 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, 
bouts 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 . 1 
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 
1 For an account of the natural movements of the Medusas and the 
effects of stimulation upon them, see Croonian Lecture in Phil. Trans. 
1875, and also Phil . Trans. 1877 and 1879. 
