CEREBRO-SPINAL NERVOUS CENTRES OF MAN. 563 



propensities in regard to food ; and the Physician frequently derives impor- 

 tant guidance with respect 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 gratification. 1 



449. Thus, then, the type of psychical perfection among Invertebrated 

 animals, which is manifested in the highest degree in the Social Insects, con- 

 sists in the exclusive development of the Instinctive faculty that is, of 

 automatic powers of a very simple kind ; in virtue of which, each individual 

 performs those actions to which it is directly prompted by the impulses 

 arising out of impressions made upon its afferent nerves, without any self- 

 control or self-direction ; so that it must be regarded as entirely a creature 

 of necessity, performing its instrumental part in the economy of Nature, 

 from no design or will of its own, but in accordance with the plan originally 

 devised by its Creator. 



450. On turning to the Vertebrated series, on the other hand, we find that 

 its type of psychical perfection, as shown in Man, consists in the highest 

 development of the Reason, and in the supreme domination of the Will, to 

 which all the " automatic " actions, save those which are absolutely essential 

 to the maintenance of the Organic functions, are brought under subjection ; 

 so that each individual becomes not only a thinking and reflecting, but a 

 self-moving and self-controlling agent, whose actions are performed with a 

 definite purpose which is distinctly before his own view, and are adapted to 

 the attainment of their end by his own intelligence. This, however, is only 

 true of Man in his most elevated state; and not only in ascending the Ver- 

 tebrated scale, but also in watching the progressive evolution of his mental 

 faculties during the earlier periods of his life, may we trace a regular grada- 

 tion, from a condition but little (if at all) in advance of that of the higher 

 Invertebrata, up to that which is displayed in the noblest examples of Hu- 

 manity. Through the entire series, however, we perceive that the Excito- 

 motor and Sensori-motor portion of the Nervous system ( 453) constitutes 

 its fundamental and essential part; serving not merely as the instrument 

 whereby those actions are performed, which are as necessary among the 

 higher animals as they are among the lower, for the maintenance of the 

 Organic functions; but also as the immediate recipient of all those impres- 

 sions from without, by which the higher operations of Mind are excited, and 

 as the executant of the actions which proceed from them. But as we ascend 

 the Vertebrated scale, or as we watch the progressive psychical development 

 of the Infant, we find it becoming more and more obvious that the actions 

 are prompted, not so much by simple sensations, as by ideas or notions of 

 the objects to which they relate ; these ideas being founded, in a large pro- 

 portion of instances, upon the results of past experience, and the course of 



1 We have not, perhaps, any right to affirm that there is nothing whatever uuulogous 

 in the Invertebrata to the Keasoning powers and Will of higher animals; but if 

 these {'acuities have any existence among them, they mu.-t be regarded as in a merely 

 rudimentary state, corresponding with the undeveloped condition of the Cerebrum. 

 The only distinct indication of intelligence displayed by Invertebrata, is the slight 

 degree of capacity of "learning by experience" which some of them display; this 

 capacity being limited to the mere formation of associations between the psychical 

 called up by different objects of sense, which we observe to be the first stage in the 

 development of the mental powers in the Human infant. 



