420 



SCIENCE. 



[Vol. XIV. No. 359 



cated. This peculiar behavior with water explains the impossibil- 

 ity of preparing the fluoride in the wet way. 



When the anhydrous fluoride is heated to bright redness in a 

 platinum tube closed at one end, fluorine at once begins to be 

 evolved as gas ; and, if a crystal of silicon be held at the mouth of 

 the tube, it takes fire, and burns brilliantly in the gas. The resid- 

 ual platinum is found, on examining the contents of the tube, to 

 consist of distinct crystals of the metal. Hence by far the most 

 convenient method of preparing fluorine for lecture purposes is to 

 form a considerable quantity of the fluoride, first, by passing the 

 product of the electrolysis over bundles of platinum wire heated to 

 low redness, and afterwards to heat the fluoride thus obtained to 

 full redness in a platinum tube closed at one end. It only remains 

 now to discover another method of preparing fluoride of platinum 

 in the dry way, to be able to dispense with the expensive electroly- 

 sis apparatus altogether. M. Moissan has also prepared a fluoride 

 of gold in the same manner. It is likewise very hygroscopic, de- 

 composable by water, and yields gaseous fluorine on heating to 

 redness. 



MENTAL SCIENCE. 

 Diseases of the Memory. 



Cases of amnesia, or the loss of a small or large portion of the 

 contents of the mental storehouse, have been observed from very 

 ancient times, and have always attracted attention. The decline of 

 mental powers brought on by old age is frequently introduced by 

 a failure of memory. When, however, this sets in at an earlier 

 period, and develops rapidly and to an extreme degree, we recognize 

 an abnormal and striking phenomenon. The possibility of such loss, 

 particularly when following a purely physical cause, such as a blow, 

 a fall, or other accident, could not but suggest the physiological 

 counterpart of the memory process as something very material. 

 To-day we attempt to analyze such cases more minutely, recog- 

 nizing in the diseases of memory a natural experiment that throws 

 light upon the laws of mental growth and decay, the interrelation 

 of the various avenues of knowledge, as well as the nexus of men- 

 tal function with anatomical characteristics. In all these aspects 

 a recent study of diseases of memory by Dr. Korsakoff of Moscow 

 {Revue Philosophigue, November, 1 889) is interesting. 



The first case described is that of a Russian writer afflicted with 

 multiple neuritis, — a nervous disease affecting many groups of 

 fibres, as a consequence of alcoholic excess. When the patient 

 was first seen, the trouble was very marked. He had completely 

 forgotten all recent events : he did not even remember whether he 

 had dined or not. The conversation just held was at once for- 

 gotten ; and, when outsiders insisted that such and such things 

 happened that the patient had forgotten, he lightly remarked that 

 he always had a poor memory. Very striking is the fact that every 

 thing previous to the onset of the disease he remembers clearly. 

 Of a novel that he was writing at the time, and had half finished, 

 he remembers the first half, but does not remember how he intended 

 to finish it. Though the domain of his thoughts is limited, his 

 reasonings are logical, and his judgment sound. But a slight inter- 

 ruption in the conversation will make him forget what it was 

 about ; and he will say the same things over and over again, using 

 the same stereotyped forms of expression, and forgetting that Ke 

 has said it. Moreover, under the influence of certain external 

 stimuli, certain positions and suggestions, he will always make the 

 same remarks, in which he draws upon the old storehouse without 

 adding to it. There are indications, too, that to a slight degree the 

 unconscious registration of impressions is going on. Thus, though 

 he forgets Dr. Korsakoff between each visit, he always makes the 

 remark (regarding it as original each time) that the latter is a 

 physician. Emotions and feelings make more of an impression 

 than facts and associations. A post-mortem examination in this 

 case showed degeneration of both fibres and cells, which had also 

 been inferred from paralysis and other symptoms observed in the 

 patient. 



Impairment of memory is characteristic of this disease ; the mem- 

 ory for recent events being lost, while that for events antedating 

 the attack remains, and the patient retains judgment and reason- 

 ing power. The same patient who forgets that he has dined five 



minutes after leaving the table can play cards or checkers with fair 

 skill, anticipating the consequences of his or his adversary's plays, 

 and following out a plan of attack or defence. If the game is 

 slightly disturbed, he cannot go on. The moment he is through 

 playing, he knows nothing of it, and will declare he has not played 

 for a long time. The contrast between the past and the present is 

 sharply brought out in one patient who tells of his travels at great 

 length, but repeats the tale a dozen times an hour, and always with 

 the same phrases. Sometimes the patient does not even recall that 

 he is ill, explaining a paralysis as a momentary cramp in the legs, 

 and expressing his intention of rising as soon as that has passed. 

 The same patient will cry out under his pain, but a moment later 

 will have forgotten the sound and the pain. To show how slight 

 an interval is needed for the impression to disappear, it may be- 

 mentioned that this [patient, in reading, will read the same line- 

 twice, having forgotten the one line before setting out upon the 

 next. Those who are constantly with such patients soon get to 

 know what they will say upon the usual occasions. Their life is- 

 monotonous, — a response to the suggestions from the outside, and 

 not originating from internal impulses. They are frequently con- 

 scious of their infirmity, and anxious lest they commit some indis- 

 cretion. 



Dr. Korsakoff thinks, that while the patient does not consciously 

 remember what is going on, yet the surrounding events leave some 

 trace by which future conduct is influenced. Thus a patient who 

 was undergoing an electric treatment, and forgot all about it each 

 time, not being able to tell what the doctor was about to do, if 

 asked to look about him, recognized the apparatus and its purpose, 

 which he did not know before his illness. Another patient, who- 

 said " Good-morning ! " when the doctor made his first visit of the 

 day, did not remember the visit three minutes later, but did not 

 then say " Good-morning ! " The most convincing proof of this, 

 however, appears when recovery sets in, and the patient begins to- 

 tell some httle of what happened during his illness. In one case a 

 sphygmograph was described, — an instrument the patient had 

 seen only during his amnesic period. Emotional states seem the 

 ones most susceptible of this unconscious perception. While the 

 patient forgets his visitors from one time to another, yet he meets 

 them with sympathy or antipathy, according to previous experiences ; 

 or, again, a patient who was treated with electricity remembered 

 nothing of it, but was always put into a bad humor when he saw 

 the machine. 



In the process of recovery, usually quite gradual, several inter- 

 esting phenomena appear. Frequently the patient begins to re- 

 member events, but in isolation. He cannot tell what happened 

 just before or just after. "He cannot tell when things happened ; 

 as a rule, regarding all things as more recent than they really are. 

 When he begins to remember new faces and places, he still con- 

 tinues to repeat the same sayings again and again. He will be able 

 to say that he has read a certain thing, but does not remember 

 what it contained. Though not able to recall the events of his ill- 

 ness at will, an incident or a suggestion may bring it up. Little by 

 little his past is filled out, though in a somewhat chaotic manner ; 

 dreams and the products of his imagination intermingling with real 

 events without definite relation in time. He frequently continues 

 to believe what has no basis in fact. His recovery is often a 

 matter of two or three years. In another case, after five years the 

 memory of the patient continued weak. He was able to resume 

 his occupation of correcting sheets for the press, but had to keep 

 his finger on the lines so as not to go over the same line twice. He 

 even began to practise law, though he was compelled to avail him- 

 self of all sorts of memoranda, and was frequently perplexed by 

 forgetting what he had said ; yet he was able to conduct himself 

 consistently. The memory for places, streets, and houses, locali- 

 ties in general, is restored long before that for time. 



Dr. Korsakoff next attempts to analyze just what factor in mem- 

 ory is affected, concluding that it is simply the power to recall im- 

 pressions ; the facts above cited showing that the impression is 

 made, though very faintly. Moreover, as recollection is based upon 

 association, those ideas being most at command that have the 

 widest and deepest associative connections, the defect is referred 

 to that portion of the nervous system instrumental in connecting 

 nerve-centres with one another. Into a more detailed and neces- 



