The second class of muscular motions are the involun tary, or those which originate in something which acts upon the muscle independently of the will ; to this class belong the contraction of the heart and of the diaphragm, and generally of those muscles which arc subservient to the vital functions. The contractions of the muscular ex pansions are involuntary, as well as of the muscular fibres that are attached to vessels of all descriptions. Although there are some muscular organs that partake of both these kinds of motions, yet, for the most part, each one has its appropriate action, either voluntary or involuntary. It hence becomes a question on what this difference depends; \vhether there be any thing in the structure of the muscle itself, or in its connexion with any other part, which can account for this difference of action. Although there is a considerable difficulty in determining this point, as indeed is the case with every thing that respects this department of physiology, it appears probable that the difference de pends, in part at least, upon the kind of nerves that are sent to the muscular fibres, and especially, whether the nerves proceed immediately from the brain and spinal marrow, or from some of the ganglia. As a general fact, it may be stated, that the nerves which place a muscle un der the control of the will, proceed from the former source, while the mere sensibility of a part is produced by its nervous connexion with the ganglia. The muscles of speech and of locomotion, in a sound state of the body, are completely voluntary ; those that belong to the vital functions are involuntary ; while the organic functions are immediate between the two in this respect ; and it will be found that the origin of their nerves corresponds general ly to their degree of voluntary power.
Among the parts of the animal economy which serve as a connecting link between the physical and intellectual functions, we may place the passions. Although, in the first instance, they belong exclusively to the intellectual functions, yet they depend so much upon our corporeal organization, and have so powerful an influence over it, that they become an interesting object of attention to the physiologist. The passions depend for their existence upon the combined operation of impressions made upon the external senses, and the previous state of the nervous system, either as derived from• original organization, or from the effect of previous impressions. But in whatever way the passions be themselves excited, it appears to be on the organic functions that they exert their influence. An impression made upon the eye, combined with some previous idea of pain or danger, produces the passion of fear, and the effects of fear manifest themselves upon the action of the heart, causing it to throb violently, or al most to suspend its motion, according to the constitution of the individual, and the degree of effect produced. Nor is it upon the circulation alone that the influence of the passions is experienced ; the respiration is no less under their influence, and is affected in an equally evident man ner by surprise, while there are other emotions which pro duce their appropriate operation upon the digestive or se cretory organs. It follows, from these considerations, that the passions are, in a great measure, innate, or that different individuals, although placed in the same circum stances, will have different passions excited, or, at least, different degrees of the same passion. But it is not only the organization which influences the passions, the reverse -r this operation takes place ; the passions have the power of d, of course, the functions depending upon it. If a violent emokinn of any kind pro duces a temporary derangement of the stomach, it is easy to suppose that a continued action, or frequent recurrence of these feelings, may permanently affect it, producing, in the first instance, a functional, and at length a structu ral disease of the organ.
The remarks which have been made above, respecting the connexion between the physical structure and the in tellectual functions, lead us to the subjects of craniology and cranioscopy—topics which have of late exercised so much of the ingenuity both of the anatomists and the physiologists. These sciences are founded upon the po sition, that the character of the individual depends upon the structure of the brain ; that this affects its external form ; and that this form, and consequently the charac ter, may be detected by an examination of the skull.
Many insulated facts had been observed which appeared to countenance this doctrine, but it was not until the pub lication of Dr. Gall that these speculations assumed a re gular form, and were entitled to the rank of a scientific hypothesis. This writer, in conjunction with Dr. Spurz heim, endeavours to prove, that particular faculties of the mind have their seat in particular parts of the brain, and that the individual will be distinguished for certain fa culties, according to the proportional size of the ap propriate cerebral organ. It is farther maintained, that these organs are seated in the convolutions of the cere bruni ; that they impress their form and size on the skull ; and may be perceived by an external examination of the head.
This subject involves several topics of inquiry, which are, to a certain extent, independent of each other. We must first inquire, whether there actually be this division of the brain into distinct parts, each serving as the seat of an intellectual function ; in the second place, whether these organs be situated in the external part of the cere bral mass and, thirdly, whether they can impress their form upon the skull, so as to admit of being detected by an examination with the hand. The controversy which has been excited on this subject can only be determined by the careful examination of facts, and the proper deduc tions from them. We should observe the effects of par tial diseases or injuries of the brain, noticing their con nexion or correspondence with the different faculties ; and conversely, in those cases where individuals have exhibit ed very strongly marked characters, either from the un due manifestation of certain faculties, or from their ab sence, we must endeavour to learn how far the brain and the skull have possessed a figure which would have ena bled us to detect them. To a certain extent this has been attempted by Drs. Gall and Spurzheim, and is professedly the basis on which they have built their hypothesis ; but we conceive that they have been too little careful in the selection of facts, and too hasty in their generalization of them. At present, therefore, we shall not venture to decide upon the truth of the doctrine, and shall only re mark concerning it, that we think there are some strong facts which tend to the conclusion, that the functions of the brain are rather attached to the whole, as one organ, than to each of its individual parts ; that it is antecedently more probable that the internal parts of the brain should be the seat of its different functions, provided this divi sion of functions actually exists ; and farther, we are dis posed to regard the classification and arrangement of fa culties, which have been proposed by the advocates of the doctrine, as not those which would follow from a correct knowledge of the human understanding. It will be obvi ous that some of these objections apply to the doctrine it self, while others are rather to bo concidorod os belonging to the method in which it has been developed by Dr. Gall and his disciples.
The science of physiognomy is nearly allied to that of cranioscopy, so far as it professes to judge of the internal faculties by external characters ; but it employs a differ ent set of parts for this purpose, viz. the form and ex pression of the face. It must be admitted as a matter of fact, that all persons of any degree of reflection are phy siognomists ; that they form an opinion of the character of individuals from the inspection of their countenance; and that they do this, as it were, involuntarily, by having acquired an experimental conviction of the truth of their observations. And it is not difficult to account for this correspondence between the character and the expression of the countenance. The muscles of the face are the great instruments for expressing the passions; and when any passion is strongly excited, and frequently repeated, the soft parts acquire a tendency to certain positions, even when the corresponding emotion no longer exists. Nor is it going beyond the limits of probability to assume, that the tendons, and even the hard parts, may have their form permanently altered by the action of the muscles, so as not merely to produce a permanent change in the expres sion of the features, but even, in some measure, to alter the shape of the face.