Reason and fasti net. 



6435 



to the situation of the bait, and select the particular one that pleases 

 it best. ,, 



Proceeding now to the Mollusca, we find in the lowest class of this 

 department no very striking advance in nervous development over the 

 creatures last noticed ; but as we proceed with our investigations in 

 the higher classes, we meet with what either is or may be regarded as 

 a brain proper. A certain ganglion receives an accession of size, and 

 at the same time is evidently charged with the performance of certain 

 distinct functions, such as are unquestionably discharged by the true 

 brain. But I cannot do better here than avail myself of Mr. Couch's 

 able and lucid statement on this part of our present subject. " In 

 this manner in the Molluscan Conchifera, there is a ganglionic dis- 

 tribution to the single organ termed the foot, by which voluntary 

 motions are elicited ; and we are thus enabled to judge that this 

 enlarged portion answers to at least a portion of the cerebellum : and 

 this is the earliest development of real brain to be met with in the 

 ascending scale ; and the advancement undoubtedly does not consist 

 in the mere increase of size, but in an acquirement of some additional 

 organization. The common mussel (Mytilus Edulis) possesses this 

 foot and corresponding ganglion ; and, therefore, though not capable 

 of positive change of place, it is able to extend and direct the organ 

 in such a manner as, with some approach to consciousness, to direct 

 the application of its mooring threads or byssus, so as to secure stability 

 of situation. The oyster, Anomia and kindred genera, which remain 

 fixed by calcareous adhesion, are destitute of the foot and the 

 ganglion, and are consequently among the lowest in the scale of nature 

 of molluscan animals. But in the highest of these orders or families, 

 the Gasteropods or cuttle fishes, not only is this nervous system much 

 more highly organized and developed, but the ganglia begin to assume 

 the form of a real brain, inclosed in a defensive case approaching to 

 the nature of a cranium ; and accordingly their faculties of intelligence 

 and passion approach closely to those of fishes. They are capable of 

 manifesting some degree of curiosity, as is seen in their moving up to 

 a shining object to examine it ; and in the presence of danger they 

 become suddenly suffused with a decided blush of red, and then eject 

 the contents of their ink-bag, by which they become shrouded from 

 observation and baffle pursuit." — 6 111. Instinct,' pp. 10, 11. 



Now it may be fairly remarked here that these creatures not only 

 exhibit, in their actions, indications of Instinct in respect of fear, 

 food-craving, sexual love, hybernation and local direction, but also, 

 from time to time, at least faint traces of a power of action with an end 



