temporary association of nerve cells; but were we able to trace the nervous impulse, thru all its intricacies, to the brain centers, did we know the exact molecular changes which cause the efferent impulse, -the nature of a thought would be as much a mystery as ever. Indeed it is doubtful if the question is ever solved by the finite mind. Tyndall said: "There is no fusion possible between the two classes of facts. The passage from the physics of the brain to the corresponding facts of consciousness is unthinkable." It is not claimed that the unknown is necessarily the unknowable, but it is a line of investigation which cannot be taken up in any superficial way. This confession of ignorance is in fact a great step toward a higher knowledge. It is a refined agnosticism. The fact seems to be that the brain is the organ of the mind, just as the body is the organ of the brain. SENSATION Simple protoplasm possesses irritability, contractility, and elasticity that is, it has sensation equal to its needs. Professor Sutherland has said: "A nervous system is an arrangement by means of which an organism becomes conscious of its environment (food, friends, and foes) and adapts itself thereto." I This is a very comprehensive definition suited to any form of life except unicellular organisms, and even here, altho there is no aggregation of nerve 'Anatomical Lectures, B. U. Med. School. elements into a system, yet monocellular forms react to touch, pressure, etc. When the ameba envelops and ingests the food particle that touches its periphery, it evidences a "consciousness of environment and adjustment thereto." It is evident that the word consciousness is here used in a general sense. Some psychologists have restricted the term to define a human attribute only, and others have asserted that consciousness without a central nervous system is impossible. From a biological standpoint all life is conscious. REASON AND INSTINCT By studying the evolutionary scale of life as it exists to-day, it is seen that the nervous system, like its accompanying organism, progresses from the simple to the relatively complex, till in man it reaches a development capable of what we call reason. Undoubtedly psychology has drawn too sharp a line between reason and instinct. The reaction from this was the contention that the lower animals reason, the difference being one of degree, not of kind. The earlier idea that reasoning was an attribute of man only was natural in preëvolutionary times, and was based on the belief in the immediate creation of perfected organisms, the so-called special creation, because special creations had distinct endowments. The evolutionist maintains that since the establishment of the general law, "from the REASON AND INSTINCT 5 simple to the relatively complex," the burden of proof rests on him who claims that at any time or place it ceases to be of universal application. Perhaps no one has a right to affirm that gravitation is of universal application, and yet experience warrants one in assuming its universality as a working hypothesis till an exception is proved. So it is assumed that the development of the nervous system has been one continuous upward movement, till we have the mind of man. This would lead us to expect to find the difference between reason and instinct one of degree, and in the last analysis this may be so. Evolution teaches that certain species have become side-tracked, and are forever consigned to inferior positions. These are the animals whose mentality never rises above the plane of instincts. As morphological connecting links are wanting, so in a still more emphatic way is there a gulf between the highest instinct and the human mind. Professor James says: "No actions but such as are done for an end, and show a choice of means, can be called indubitable expressions of mind.” Accepting this criterion, that in order to be classed as reason an act must "show a choice of means," it is possible to draw a sharp line between reason and instinct. It is somewhat generally believed that instincts are attributes of the lower animals only, and the fact is overlooked that man is richly endowed in this direction, especially in infancy. Instincts are impulses. "Theirs not to reason why." In physiology we call them reflexes. The human infant is born with the instinct to suck fully developed. The tendency to clasp any object that comes in contact with the fingers or toes is very marked. In fact, this instinct is stronger a few hours after birth than at any later period. New-born children are able to sustain their own weight by grasping a lead-pencil, often with only one hand. The evolutionary bearing of this is very interesting, and shows very beautifully how natural selection could, in the lower animals, propagate this impulse. The young of the chimpanzee whose grasp of the mother was strongest would by this means escape destruction when pursued by an enemy. Of course in man the law of the "survival of the fittest" is operative in a lesser degree. The transiency of many infantile instincts, when not exercised, will be again referred to under the subject "Habit." Fear and love we possess in common with the animals. The sexual passion is perhaps one of the strongest examples. DO ANIMALS REASON? Let the great John Burroughs answer it. "Apropos of the question, ' Do animals think?' a correspondent, writing from Washington, says that I deny this power to the lower animals because I use the word in a too restricted sense. He then REASON AND INSTINCT 7 proceeds to say that if we use the word 'chin' to signify exclusively a portion of the human face, meaning that portion which is extended perpendicularly downward from the mouth, we would hesitate to say that lower animals have chins. So if we define "laugh" as spreading the mouth in merriment we could not say that animals laugh.' "I am quite ready to admit that animals think in as strict a sense as they have chins or as they laugh. A feeling of play and merriment they certainly have, but this feeling is practically entirely physical. I don't suppose an animal could appreciate a joke, or the comic, or the absurd. Man is the only animal that laughs or weeps, though tears may run from the eyes of a suffering beast. And the chin of a bird or beast is a very rudimentary affair indeed. "Take the case of the little yellow warbler when the cowbird drops her egg into its nest - does anything like a process of thought or reflection pass in the bird's mind then? The warbler is much disturbed when she discovers the strange egg, and her mate appears to share her agitation. Then after a time, and after the two have apparently considered the matter together, the mother bird proceeds to bury the egg by building a new nest on top of the old one. If another cowbird's egg is dropped in this one, she will proceed to get rid of this in the same way. This all looks very like reflec |