THE CEREBRUM, AND ITS FUNCTIONS. 749 



nipple, and puts its muscles into suctorial action, without any knowledge that 

 by so doing it will relieve the uneasy feeling of hunger ; and if we could imag- 

 ine a man coming into the world with the full possession of all his faculties, 

 we may feel tolerably certain that he would not wait to eat until he had learned 

 by experience his dependence upon food. We have seen that adult animals, 

 whose Cerebral hemispheres have been removed, will eat food that is put into 

 their mouths although they will not go to seek it ; and this is the case with many 

 Human idiots. When the functions of the Brain are disturbed, or in partial 

 abeyance, as in fever, we often see a remarkable return to the instinctive pro- 

 pensities in regard to food ; and the Physician frequently derives important 

 guidance as to the patient's diet and regimen (particularly as to the administration 

 of wine) from the inclination or disinclination which he manifests. So, in 

 regard to the intercourse of the sexes, the impulse which prompts to it does not 

 arise from a knowledge of the ultimate purposes which it is designed to answer; 

 and the higher powers of the mind are only so far concerned in it that, when 

 the action of the instinctive impulse has led to the formation of a definite idea 

 of the object of desire, the Intelligence is prompted to take means for its grati- 

 fication. 



780. It is not always easy to say, in the case of the lower animals, what parts 

 of their actions are to be attributed to automatic impulses (i. e. to be considered 

 as Instinctive), and what should be regarded as the results of Intelligence. In- 

 stinctive actions, however, may be generally distinguished from those which are 

 directed by reason, by the following characters : (1) Their unvarying con- 

 stancy in the different individuals of the same species, and the absence of any 

 such change, during the progress of life or in the succession of generations, as 

 indicates that the original plan of action has been intentionally departed from : 

 (2) by their occurrence under circumstances which altogether forbid the idea 

 that any past experience can have suggested the design, or that, in carrying it 

 into effect, there has been a gradual perfectionizing of the means : these actions 

 being performed as well when first attempted, as after the most frequent repeti- 

 tion : (3) by their occasional performance under circumstances in which the 

 least Intelligence would indicate their absurdity as being nugatory for the ends 

 they are originally destined to accomplish : as when a tame Beaver attempts to 

 build its dam across a room, or when a community of Bees, having killed their 

 Queen because she only lays drone-eggs, attempts to make a new queen from one 

 of the drone-larvae. The character of Intelligent actions, on the other hand, is 

 shown (1) in the variety of means which may be adopted to compass the same 

 ends, and this not merely by different individuals and by successive generations, 

 but by the same individual at different times ; (2) by the improvement in the 

 mode of accomplishing the object, which results from the intelligent use of ex- 

 perience, and from the greater command of means which is progressively at- 

 tained ; and (3) by the conformity of the means to altered circumstances, so 

 that the character of adaptiveness is still maintained, however widely the new 

 conditions may depart from those which must be considered as natural to the 

 species. 



781. The difference between actions of a purely Instinctive character, and 

 those which proceed from the Intellectual faculties prompted by the instinctive 

 propensities, is well seen in comparing Birds with Insects. The Instinctive 

 tendencies of the two classes are of nearly the same kind; and the usual arts 

 which both exhibit in the construction of their habitations, in procuring their 

 food, and in escaping from danger, must be regarded as intuitive, on account of 

 the uniformity with which they are practised by different individuals of the 

 same species, and the perfection with which they are exercised on the very first 

 occasion. But in the adaptation of their operations to peculiar circumstances, 

 Birds display a variety and fertility of resource far surpassing that which ia 



