electrically driven Baltzar kymograph and an electric circuit, including a Deprèz signal and an electro-magnetic hammer, he secured a record of sixty successive reactions made within an interval of two minutes. The stimulus recurred regularly at intervals of two seconds. The subject reacted to the stimulus as soon as possible, and the record of stimulus and reaction left on the rotating cylinder showed how much time had intervened between the two. The hammer could be replaced by a Geissler tube or a simple shock apparatus when it was desirable to use other kinds of stimulation. By means of this apparatus, Patrizi obtained a graphic record of the degree or goodness of the attention, since (other things equal) it is evidently inversely proportional to the time of the reaction. The method has also the merit of investigating attention under purer conditions than are found in other methods, because the quick recurrence of the stimulus helps very much to prevent the wandering and "unpreparedness" of the attention. And the fact that "the stimuli given are always well above the limen of any sense department, eliminates the effects of the adjustment and muscular fatigue of the peripheral sense organs that have complicated all the experiments on oscillations of attention." Experiments performed by Patrizi's method could be advantageously compared with those by another method in two ways: (1) It can be used to find the comparative value of different distractions; and (2) after the value of the distraction is known, the relations of different degrees of attention and inattention shown in the numerical results of one method can be verified or modified by the graphic results of this other method.

In closing we wish to give brief notice of "An Investigation of the Distraction of Attention" made by Bertels.' It is the only thesis on the subject that we have yet come across, and deserves consideration on that account. But the author's work does not touch the problems with which we have been dealing. Bertels started with three questions in mind. "1. How is distraction affected by the intensity of the distracting stimulus? 2. How is it affected by the interval between the test-stimulus and the distracting stimulus! 3. How is it affected by the quality of the distracting and the test-stimuli?"2 But he had time to investigate only the second question-the effect of the in tween the two

"Versuche über die Ablenkung der Auf A. Bertels.

2 Op. cit., p. 10.

1

Dorpat, 1889.

1

stimuli. Visual stimuli were used in all the experiments. The distracting stimulus, as well as the test-stimulus, was given only for a moment. Light was admitted for an instant into a tube leading to one eye, and then after an interval, light was admitted to another tube containing two Nicol prisms. The distracting effect of the first stimulus was measured by the angle through which one of the Nicols had to be turned before the second light could be discerned. The most important result of his experiments was the discovery that the first stimulus acted more as a signal-stimulus than as a means of distraction. It distinctly aided the attention, most of all at an interval of 23 seconds, and at intervals that were multiples of this number. So that the thesis tells us nothing with regard to distraction, except that what was expected to act as a distraction acted otherwise.

Summary of the four chapters.

The introductory chapter briefly discussed certain physiological concepts, which play an important part in theories of attention; i. e., the question of the nature and extent of cerebral localization, and the question of neural reinforcement or facilitation (Bahnung), and neural inhibition (Hemmung).

The second chapter analyzed the "descriptive" theories of attention, or those which deal chiefly with the effects and secondary phenomena of attention. These theories describe attention as merely motor (Ribot and Münsterberg), merely sensory (Bastian, Marillier, etc.), or as sensori-motor (Waller). The discussion of these three classes involved reference to the controversy over sensory and motor centres in the cortex, the correlation of consciousness with efferent nerve currents, and allied topics.

3 In the third chapter the "explanatory" theories of attention were presented-those which seek for the fundamental principles in the process. The three types found here regard attention as a facilitation (G. E. Müller), as an inhibition (Wundt and Külpe), or as a combined facilitation and inhibition of stimuli (Exner). After a review of each theory separately, we discussed the fundamental differences between them, and especially the problems still left unsettled by one or all of these theories. Some of the most important topics were the relation between attention and the increased clearness of an idea, the "feeling of activity," inhibition, associative co-excitation, reinforcement or facilitation, changes in intensity due to attention and due to variations in the stim

The fourth and last chapter, under the title, "Attention and Distraction," gives an account of an experimental investigation of the effect of so-called distractions on sensible discrimination. The experiments are, in part, a repetition of those made by Prof. Münsterberg in his study of "Attention as Intensifying Sensation." The negative and critical results of our work show that the experiments do not sustain Prof. Münsterberg's conclusion that "all stimuli appear relatively less when attention is directed to them from the outset." (1) The distraction acted more often as an incentive or spur than as a check to the attention, and this fact renders the experiments worthless for their original purpose; (2) Disturbing factors were noticed which materially affected the numerical results. These factors were not considered, and no precautions were taken against them in the original experiments. Among the most important we would mention the effects of the presence or absence of distinct memory images, different ways of treating the distraction, and different methods of judging weights. (3) The original experiments treat only a certain kind of attention, expectant, and a certain degree of this, too much expectancy; their results, even if they were wholly accurate, could not apply to attention under any other conditions. (4) An unscientific treatment of the numerical results destroys the force of any psychological conclusions based upon them. The positive results of our work have taken the form of certain directions advisable for further experimentation. They refer: (1) to a pre-adjustment of the attention; (2) to the continuity of the distraction; (3) to methods for remembering stimuli; (4) to the testing of results obtained from one method by those secured from other methods. The chapter closes with brief mention of an earlier study of distraction by Bertels.

OLD AGE AND DEATH.

BY COLIN A. SCOTT,

Late Fellow in Psychology, Clark University.

Biological. From the most general point of view it must be admitted that senescence is a constant accompaniment of development. The evolution of both the race and the individual is as much concerned with the effective dismissal of old and ante-dated organs as with the production of new ones. 1 Minot2 indeed regards the whole course of individual life from the moment of the union of the two reproductive cells as a gradual decay, and has attempted by elaborate weighings to prove that during the minority or period of growth of guinea pigs, the actual vital force diminishes steadily. At the same time we must not lose sight of the fact that senescing cells, such as glandular products and organs like the gill-slits, etc., of the vertebrata, exercise a stimulating influence upon the organs which remain or take their place. Their force is passed on rather than lost, and while decay is undoubtedly a constant and necessary factor in all vital manifestations, and whatever may be true of the ultimate "vital force," it must be admitted that the functions of life as they may be observed in any specialized organism, increase for a time in strength, range, and complexity, pass through a period of comparative poise, and finally break up and disappear. These three natural periods, however further they may be divided (Cf. Flourens, e. g.) are emphatically punctuated by the advent and decline of the sexual and reproductive functions, which may thus be regarded as crowning the physiological development of the individual.

In many species, however, as Weissmann, Goette, Geddes and others have pointed out, the closing stage is wanting. There is no gradual senescence, but death

'The ability to forget, e. g., is as important to psychic health as the capacity to acquire. Cf. paragraph on the funeral.

Jour. Phys., May, '91, and Biologisches Centralblatt, XV, No. 15.

follows immediately upon the completion of the reproductive functions. Weissmann regards this as due entirely to external conditions operating upon the individual through natural selection, and tries to show that death is a favorable adaptation to get rid of senility, which he thus accepts as fundamental and due to a wearing out." Goette1 on the other hand regards death as the fundamental fact, a necessity inherent in life itself, an unavoidable consequence of reproduction, and represented in the protozoa by encystment and rejuvenation. Death must, he says, have become necessary and hereditary in a number of individuals before it could possibly become useful and thus operated upon by natural selection. Senility he regards as having been "acquired in the course of development of the race."4

2

But it is impossible to separate, as Weissmann does completely and Goette to a less extent, the individual and its environment. A view which combines the internal physiological causes of Goette and the external, natural selection, or teleological causes of Weissmann as both necessary and complementary to each other, is the only one which can have any application to organisms as they at present exist. The point of fundamental importance brought out by both Goette and Weissmann is that death and senility are ultimately functions of the species, primarily of phylogenetic importance, whether regarded as being originally necessary to the continuance of life, or impressed upon it from without, and enter the life of the individual as such, in connection with the sexual and reproductive functions.

Stylonichia pustulata, protozoans, are interWeissmann's view of

The experiments of Maupas5 with one of the most highly developed preted by him (in opposition to the immortality of the protozoans) as demonstrating the fact of senile degeneration followed by death in these animals. S. pustulata multiplies by division at a temperature of 24° to 28° C., dividing as often as five times in twenty-four hours.6 Beginning with an individual which had just conjugated, Maupas followed the multiplication to the 313th division when he had 510 individuals. He

'Life and Death, "Biological Memoirs," p. 135.

"Ueber der Ursprung des Todes."

3 Op. cit., p. 6.

4

Op. cit., p. 54.

5 Recherches expérimentales sur la multiplication des infusories ciliés, in the Archives de Zoologie expér. et gen., 1888, No. 2.

"If all of the resulting individuals could be nourished to the fiftieth generation, that is, in thirty days, there would be one followed by forty-four zeros, which, if united in one mass, would make a sphere a million times greater than the sun in volume.