hardly be otherwise explained, than by assuming that the anatomical seat of each, is the same portion of brain, or portions closely adjacent. Though the above facts show the probability of such an arrangement (and it is also in conformity with the other processes of the mind, as will be shown in the following chapters), they do not afford direct evidence that such is the case; but there is evidence, and evidence of the most positive character, and it is this: under certain conditions the memory for a definite period of time is lost.

Numerous cases are on record of a person receiving some great shock, and on recovery being found to have lost the memory, not only of the circumstance which gave rise to the shock, but also of a certain period of time directly preceding it, all the events and circumstances which happened during that time being forgotten, the last circumstance remembered, preceding the blank, often being some trivial incident.

The following are excellent illustrative cases:

1. The ensuing is taken from Mind, October, 1887, p. 636. It is especially important on account of its happening to, and being related by, such an eminent psychologist and accurate observer as Professor Bain. He gives the following account: "On October 23 last I rode out on horseback. The horse stumbled and fell. A labourer in an adjoining field saw the fall 1 ; on running up, he found me overlaid by the horse, and dragged me out insensible. I was taken to the adjoining farmhouse, and was found to have sustained various injuries, the worst being a bad dislocation of the right shoulder. The insensibility continued upwards of three hours, during which time my shoulder was set without pain or knowledge. When conscious

ness returned, the memory of what led to the accident was discovered to be completely obliterated. In fact, the loss of memory extended to a full hour previous, and it has not yet been recovered. In no other respect did the concussion leave any permanent injury to the mental faculties." Professor Bain was on a different road from that which he remembers he intended to take on his way home. He must have changed his mind, but of the change, as of all that followed upon it till the time of the accident, he has as little recollection as of the hours he lay unconscious.'

2. Then follows another interesting case of a man who was thrown from a dog-cart, and lost all remembrance of the accident and of the occurrences of the previous week, which had been of a very eventful character for him. For the details of this case, which are similar to those already given, I must refer the reader to the original.

3. The following is taken from Ribot's 'Diseases of Memory': 'A young woman, married to a man whom she loved passionately, was seized, during confinement, with prolonged syncope, at the end of which she lost all recollection of events that had occurred since her marriage, inclusive of that of the ceremony. She remembered very clearly the rest of her life up to that point. At first she pushed her husband and child from her in evident alarm. She has never recovered recollection of this period of her life, nor of any of the impressions received during that time. Her parents and friends have convinced her that she is married and has a son; and she would sooner believe that she had lost a year of her life than that all her friends and relations are impostors.'

4. The following is related by Abercrombie in his 'Intellectual Powers': A young lady who was present at a catastrophe in Scotland, in which many people lost their lives by the fall of the gallery of a church, escaped without any injury, but with complete loss of the recollection of any of the circumstances; and this extended not only to the accident, but to everything that had occurred to her for a certain time before going to church.'

5. A young lady, having ascended an iron staircase, became giddy and fell down, being afterwards found insensible at the bottom. After her recovery, she had no recollection of the cause of her illness or the place where she had fallen down. Five years afterwards, she happened to go to the same place again, and immediately the whole flashed into her mind; she remembered becoming giddy and falling.

For further examples of this class of cases, see Chapter XII., on the Pathological Conditions of Memory,' where references will be given to numerous cases. The recording cells have become damaged in some way, probably in many, if not in all cases, by the intensity of the impression giving rise to the shock, and its intensity has caused it to destroy not only the recording cells in use at the moment, but also those which have just been used. Now, in these cases, the faculties are not interfered with, and if the view be taken that the perception and memory occupy the same position, and are a part function of certain faculties, we should expect that impressions belonging to the faculties in use at the time of the shock would be destroyed, and not impressions belonging to other faculties.

It is impossible to conceive how this loss of memory

could occur, if the view stated above be not the explanation. With regard to the theory, that the remembrance occupies the same portion of the brain as the perception, many of the perceptions, received ten minutes. before, vary very considerably from those received just at the time of the shock; for within an hour, nearly every faculty of the mind is used, so that if the ordinary hypothesis be accepted, an explanation is required as to why impressions by other faculties than those employed at the time of the shock are interfered with, and why the faculties in action are not particularly affected. Further proofs, showing the impossibility of the remembrance occupying the same portion of the brain as the perception, will be given when treating of the functions of the faculties of the mind.

In the same way, it is impossible to explain the loss of memory in these cases, by supposing that there is disease of the sight, tactile, word, and other centres: to assume that this could be the case, and no other effect found than a loss of memory for a certain period of time without any other perversion of function, would be absurd. If this were the case, why should certain impressions be picked out, as it were? and why should all these be found to be those received in a definite period of time, and no others?

CHAPTER IV

MOTOR MEMORY

MOTOR memory is the memory required for the performance of co-ordinated muscular movements which have to be learnt: these include all those movements which require for their first performance (at least) an exercise of the will. This distinguishes these movements from those which are simply reflex, though the mechanism for the execution of the latter may be exceedingly complex, as in coughing. A reflex action. requires for its performance, a sensory nerve, a nerve centre, a motor nerve, and a muscle. Then, an impulse having been generated, by stimulation of the sensory nerve, is reflected at the nerve centre, and passing along the motor nerve causes a contraction of the muscle. But, this reflex action may be inconvenient to the individual, and, therefore, require suppressing, as in cases of recovery from paraplegia caused by a tumour pressing on the spinal cord: the reflex actions are found to be excessive, and continue so, even after the removal of the tumour: the contact of the sole with the ground causes an excessive reflex contraction of the calf-muscles: after a varying time this passes off, as the higher nerve centres regain control of the lower. It will be seen that if we start with a certain reflex action, brought about by a particular sensory impression, by modifica