INTRODUCTION. xxxiii 



response was due, the movements in question rival the most elaborate of non-mental 

 adjustments elsewhere performed by the most highly organized of nervous systems." 



It will be a matter of interest to trace the dawnings of mental processes in the 

 lower animals. Having seen that something more than physiological effects are trace- 

 able in certain acts of the protozoans ; passing over the sponges, which are at best 

 retrograde organisms, we come to the coelenterates, especially the jelly-fishes. In 

 none of these creatures have actions involving intelligence been observed ; all their 

 acts, so far as yet observed, are physiological, i. e. reflex, the result of stimulation 

 from without. 



Of the echinoderms, Romanes says : " Some of the natural movements of these ani- 

 mals, as also some of their movements under stimulation, are very suggestive of purpose ; 

 but I have satisfied myself that there is no adequate evidence of the animals being able to 

 profit by individual experience, and therefore, in accordance with our canon, that 

 there is no adequate evidence of their exhibiting truly mental phenomena. On the 

 other hand, the study of reflex action in these organisms is full of interest." 



It is possible that the action of the earth-worm, a representative of the annelids, 

 in drawing leaves down into its hole is " strongly indicative of instinctive action, if 

 not of intelligent purpose — seeing that they always lay hold of the part of the leaf 

 (even though an exotic one) by the traction of which the leaf will offer least resistance 

 to being drawn down." To the foregoing statement of Romanes we may add Darwin's 

 testimony as to the mental powers of the earth-worm, from his work entitled The 

 Formation of Vegetable Mould through the Action of Worms. 



" Worms are poorly provided with sense-organs, for they cannot be said to see, 

 although they can just distinguish between light and darkness ; they are completely 

 . deaf, and have only a feeble power of smell ; the sense of touch alone is well developed. 

 They can, therefore, learn little about the outside world, and it is surprising that they 

 should exhibit some skill in lining their burrows with their castings and with leaves, 

 and, in the case of some species, in piling up their castings into tower-like constructions. 

 But it is far more surprising that they should apparently exhibit some degree of intel- 

 ligence instead of a mere blind instinctive impulse, in their manner of plugging up the 

 mouths of their burrows. They act in nearly the same manner as would a man, who 

 had to close a cylindrical tube with difllerent kinds of leaves, petioles, triangles of paper, 

 etc., for they commonly seize such objects by their pointed ends. But with thin ob- 

 jects a certain number are drawn in by their broader ends. They do not act in the 

 same unvarying manner in all cases, as do most of the lower animals ; for instance, they 

 do not drag in leaves by their foot-stalks, unless the basal part of the blade is as nar- 

 row as the apex, or narrower than it." 



The next great type of animals is the molluscs. In many respects the higher 

 worms, especially the annelids, are more highly organized than the clam, a snail, or 

 cuttle-fish. The functions of sensation and locomotion are often in molluscs subordi- 

 nate to the merely vegetative, such as feeding, nutrition, and reproduction. We 

 should not, as Romanes has said, expect that molluscs would present any considerable 

 degree of intelligence. " Nevertheless, in the only division of the group which has 

 sense organs and powers of locomotion highly developed — viz., the Cephalopoda — we 

 meet with large cephalic ganglia, and, it would appear, with no small development of 

 intelligence." 



Beginning with one of the lowest molluscs, the oyster, Romanes quotes from Mr. 

 Darwin's MS, as follows : "Even the headless oyster seems to profit from experience. 



