25 



.NERVOUS SYSTEM. 



NERVOUS SYSTEM. 



23 



No one can question the completely involuntary nature of these 

 movements ; on the other hand, they are not reflex, for they do not 

 take place unless the irritation is felt. 



Xow the tickling may produce not merely a variety of semi-convul- 

 sive movements, tending to withdraw the body from the source of 

 irritation, but also a tendency to laughter, and an emotional state 

 connected with it. But it would appear that the semi-convulsive 

 movements are immediately excited not by the emotion but by the 

 sensation ; for there is a great variation amongst different individuals 

 as to the results of the irritation, the action of laughter being excited 

 in some, without any other effect ; whilst in othera, spasmodic move- 

 ments of the extremities take place without any tendency to laughter, 

 indeed with a feeling of extreme distress. 



In many Diseases the influence of emotional states are remarkable. 

 In Hydrophobia and Hysteria convulsions are frequently brought on 

 by causes that excite emotional states. In hydrophobia the sight or 

 sound of moving water will sometimes produce frightful paroxysms, 

 whilst in hysteria the sight of one individual labouring under an 

 attack will produce it in another. Many of the phenomena presented 

 by persons in the mesmeric state may be also traced to an excessive 

 activity of the consensual or emotional system, so that slight impres- 

 sions produce powerful effects. If it is also recollected that such indi- 

 viduals have frequently a morbid desire of gratifying the wishes of 

 those who witness them in the expectation of seeing marvels, a further 

 explanation is afforded of the singular phenomena presented by persons 

 in this state. 



The functions of the Cerebellum [BRAIN] have been the subject of 

 much discussion. According to the system of phrenologists [PmiK.v 

 OLOOT], this organ is the seat of the sexual instinct. This doctrine 

 derives little or no support from comparative anatomy, as there is no 

 correspondence between the size of this organ and the strength of this 

 instinct among the lower animals. Nor does it appear to be always 

 the case that there is a derangement of the sexual instinct where there 

 is disease of this organ. The more probable view of the functions of 

 the cerebellum seems to be that it is in some way connected with the 

 functions of locomotion. Its development in the lower animals cor- 

 responds with the variety and energy of the muscular movements, 

 whilst injury to this organ is invariably attended with derangements 

 in the functions of locomotion. From experiments upon all classes 

 of vertebrated animals it has been found that when the cerebellum is 

 removed, the power of walking, flying, standing, or maintaining the 

 equilibrium of the body is destroyed. It does not seem that the 

 animal has in any degree lost the voluntary power over its individual 

 muscles, but it cannot combine their actions for any general movements 

 of the body. Again, it is found that when the cerebellum is diseased, 

 the motor function of the muscles is not destroyed, but that the same 

 want of combining or harmonising the movements of the body result 

 as are observed when the cerebellum is injured. 



From what has been previously said, it will be seen that the cere- 

 bral lobes, although so important in man and the higher animals, 

 are, after nil, not the fundamental portions of the nervous system. 

 They are the last-formed portions of the nervous system, and all the 

 functions of animal life can be carried on without them. But whilst 

 this is the case there is no doubt that the cerebral hemispheres are the 

 seat of all those phenomena which we call intelligence, and which dis- 

 tinguish so greatly man from the lower animals. The substitute for 

 intelligence in the lower animals is what we call instinct. The distinc- 

 tion between actions resulting from the operation of these two princi- 

 ples are very evident. In intelligence there is an intentional and 

 known end produced, as the result of definite ideas ; whilst in instinc- 

 tive actions there are no preceding ideas and no knowledge of the end 

 to be attained. Such actions are purely automatic. Because instinc- 

 tive actions evince design, it is no proof that the animal exhibiting 

 them is aware of the design. In fact, the great mass of instinctive 

 actions are so perfect, that none of the results of intelligence can equal 

 them. The bee builds its cells with inimitable certainty ; the Clue- 

 todonroitratiu projects from its prolonged snout a drop of water, which 

 strikes the insects that arc flying above its head, and thus secures them 

 as its prey. The great majority of the actions of the lower animals 

 arc purely instinctive and automatic ; and many even of those which 

 possess cerebral lobes lead rather an instinctive than an intelligent life, 

 n with man, many of the actions of his life are instinctive, espe- 

 cially those which are performed during infancy. 



That the cerebral lobes are the seat of Intelligence, seems to be 

 proved in various ways. When they are destroyed the animal or 

 human being is no longer capable of exhibiting the functions of intel- 

 ligence. At the same time this is not the case when one lobe of the 

 braiu only is destroyed, for when this is the case from disease or acci- 

 dent, persons have been known to perform all the ordinary acts of 

 intelligence. This has led to the conclusion that just as all the func- 

 tions of eing or hearing can be performed by one eye or ono ear, so 

 all the functions of the mind may be performed by one lobe of the 

 brain. The argument* in favour of this view have been well developed 

 by Dr. Wigan in his work on the ' Duality of the Mind.' 



In cases of children who are born with a deficiency of the cerebral 

 lobe*, we find a deficiency of intellectual activity. In the case of many 

 i'liou there is simply a want of nize of brain. This is remarkably 

 exemplified in the case of the two Aztec children recently exhibited 



in London, whose brains are exceedingly small, and whose want of 

 intelligence corresponds with this deficient development of their 

 brains. It is thus that we find there is some truth in the phrenologi- 

 cal axiom [PHRENOLOGY] that the size of the brain is the measure of 

 its power. But this is only true iu respect of the gray matter, as there 

 can be little doubt that the vesicular or gray matter of the cerebral 

 lobes is the seat of intelligence. In regard to the human brain it 

 holds good as far as the operations of the understanding are concerned, 

 and persons with large heads are remarkable for the influence they 

 exercise over the judgments ami acts of others. In the case however 

 of those intellectual operations which we call Genius, and which seem 

 to take their rise in the feelings and to address the feelings, it is not 

 found that there is any relation between the size of the cerebral lobjs 

 and its manifestations, persons manifesting considerable genius 

 possessing but small brains. 



It appears to be perfectly true that varieties of mental character 

 accompany varieties in the form of the brain, and that the manifes- 

 tation!* of intelligence vary according to the temperament of various 

 individuals. 



All the operations of the mind are dependent upon sensations. 

 Without sensation there is no development of intelligence. A blind 

 man has no idea of colour : he has had no impression of colour pro- 

 duced upon his eye, and consequently no idea formed in his mind. 

 The seat of Sensorial Consciousness, as we have seen, is evidently the 

 seusorial ganglia ; but in animals without cerebral lobes there can be 

 no impressions produced, such as we call sensations : these are in fact 

 ideas or impressions produced upon the cerebral lobes by the trans- 

 mission of the impressions upon the sensory ganglia upwards. Thus 

 we find the sensory ganglia producing reflex automatic movements by 

 acting on the spinal chord below, and becoming the source of ideas to 

 the cerebral lobes above. Dr. Carpenter, to whom physiologists are 

 deeply indebted for the masterly manner in which be has investigated 

 the whole of this subject, goes farther than this, and states his opinion 

 that the sensory ganglia constitute the seat of consciousness, " not 

 merely for impressions on the organs of sense, but also for changes on 

 the cortical substance of the cerebrum ; so that until the latter have 

 reacted downwards upon the seusoriuin we have no consciousness 

 either of the formation of ideas or of any intellectual process of which 

 these may be the subjects." 



Although it follows from this that animals without cerebral lobes 

 have no ideas, we may suppose that the conditious of their conscious- 

 ness would produce the feelings of pleasure and pain ; and just as 

 these feelings are produced by external impressions, so do ideas of 

 pleasure and pain produce emotional states of the mind, which deter- 

 mine the character of our thought and influence our conduct. The 

 various sehtimeuts and propensities dwelt on by mental philosophers 

 [I'HRENOLOIIY] seem to take origin in this way, the activity of the 

 sentiment of Benevolence or Malevolence having for its excitement 

 the idea, of an object to be loved or hated, and ao on with the other 

 sentiments, and what are called the propensities. " The same view 

 may be applied to the love of Truth, of Beauty, of Sublimity, of 

 Goodness, of Order, of Possessions, of Country, &c., and also to Cheer- 

 fulness, Wit, Humour, &c., and to many conditions usually considered 

 as purely intellectual. And in fact the association of sensorial plea- 

 sure with any idea or class of ideas gives it an emotional character; 

 so that emotional states are not by any ineaus limited within the 

 categories which most psychologists have attempted to lay down; 

 these being for the most part generic terms, which comprehend certain 

 groups of ideas bearing more or less similarity to each other, but not 

 by any means including all possible combinations." 



We have seen how the movements of the body may be influenced 

 by impressions made upon the sensory ganglia, and we can now sea 

 how it is that ideas may become the source of movements. In persons 

 who are ' ticklish ' it is not necessary to tickle them to make them, 

 laugh, but the mere idea of tickling produced by pointing the finger 

 will set them off. Thus throughout the whole series of emotional 

 ideas they may be recalled without sensations so a? to produce move- 

 ments. Such movements may or may not be under the control of 

 the will. That they are not always so, that there is frequently an 

 antagonism between the emotions and the will, Dr. Carpenter regards 

 as evidence that the seat of the emotions is different from that of the 

 will. It also sometimes happens that muscles paralysed to volitional 

 will act under the influence of emotional impulses, and vice versa. This 

 subject is fraught with lessons of practical value. In the education 

 of the human being it becomes of the utmost importance so to 

 cultivate the will that it may control those tendencies to impulsive 

 action which are the result of the various emotional states. Excessive 

 indulgence in particular feelings constantly lead to those conditions 

 of insanity which are known by the name of Monomania. [INSANITY, 

 in ARTS AND So. Div.J In certain forms of hysteria, and iu habitual 

 stammering we have also instances of the loss of control of the will 

 over muscular notions, brought on by emotional states. 



The result of the activity of the cerebral lobes in the way we have 

 pointed out, is to produce what are called the Intellectual Powers. 

 To these we can only briefly refer. Thus the first in order of these is 

 called the Association of Ideas, which consists iu the production of 

 such a connection between two or mure idoaa, that the consciousness 

 of the one tends to bring the other before the miud one idea, or set 



