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McDougall that the best test of the instincts that we have is to be found in the specific emotions. He believes that every instinctive process consists of an afferent part or message, a central part, and an efferent part or discharge. At its two ends the process is highly plastic. Message and discharge, to which thought and will correspond, are modified in their type as experience matures.
It thus appears that the entire control of the circulation is effected in a reflex manner through the nerve centers in the bulb. These centers are stimulated by conditions that relate to the movement of the blood through the body. *Respiration.*—Efferent fibers connect the different muscles of respiration with a cluster of cell-bodies in the bulb, called the respiratory center.
'When the eyelids wink at a flash of light, or a threatened blow, a reflex action takes place, in which the afferent nerves are the optic, the efferent, the facial. When a bad smell causes a grimace, there is a reflex action through the same motor nerve, while the olfactory nerves constitute the afferent channels.
Locate and give the approximate number of the sympathetic ganglia. Show how the two portions of the spinal nerves are formed—the one from the mon-axonic and the other from the di-axonic neurons. Enumerate the different agencies through which the brain and spinal cord are protected. What cranial nerves contain afferent fibers? What ones contain efferent fibers?
A complex system of intermediate neurons, found mostly in the brain, join the afferent with the efferent pathways. *Choice in Voluntary Action.*—In reflex action a given stimulus, acting in a certain way; produces each time the same result. This is not the case with voluntary action, the difference being due to the mind.
Second, an affective part through which it gives rise to the emotion which is characteristic of it. Third, an efferent or conative part through which it gives rise to a characteristic type of conduct. McDougall gives a list of about twelve instincts, each with its accompanying emotion. These he regards as primary and the source of all thought and action.
Thus only can we have a true scale of standardised culture values for efferent processes; and from this we can measure the degrees of departure, both in the direction of excess and defect, of each form of work, motor habit; and even play.
If they are undeveloped or grow relaxed and flabby, the dreadful chasm between good intentions and their execution is liable to appear and widen. Character might be in a sense defined as a plexus of motor habits. Modern psychology thus sees in muscles organs of expression for all efferent processes.
The most common form of capillary angioma is the nævus or congenital telangiectasis. #Nævus.# A nævus is a collection of dilated capillaries, the afferent arterioles and the efferent venules of which often share in the dilatation. Little is known regarding the etiology of nævi beyond the fact that they are of congenital origin.
With regard to many of these movements these distinctions can be made with confidence, and in some children more certainly than in others. In childhood, before twelve, the efferent patterns should be developed into many more or less indelible habits, and their colors set fast.
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