Experiments have been made in order to test the action of alcohol on the muscles themselves, separated from the nervous system.1 With doses ranging up to the equivalent of about 70 c.c. for man, administered through the blood, no obvious effect was produced upon the contractile power or other functional properties of muscle. It is therefore inferred that any influence which alcohol in ordinary quantities exerts upon the performance of muscular acts must be referred to its effects upon the nerve-centres concerned with activating the muscle.

Alcohol depresses simple reflex reactions of the nervous system. A dose of 30 c.c, taken one to one and a half hours before the test was applied, was found to lessen the speed and amplitude of the reflex knee-jerk. As an average obtained from observations on six men, this dose of alcohol reduced the speed of commencement of the responsive movement by 96 per cent., and diminished the extent of the movement by 489 per cent. A larger dose, 45 c.c., impaired the reaction-speed and amplitude still more.2 Somewhat similar results, though of smaller percentage magnitude, were obtained with the reflex speed and amplitude of the eyelid movement when an involuntary blink was evoked by a sudden loud sound.

A slight quickening of the pulse rate commonly follows upon the taking of a moderate dose of alcohol. This acceleration appears to be due to a depression in degree of the reflex cardio-inhibitory tone which, normally, acts in restraint of the heart-beat.1 It does not, apparently, occur in all cases.

1 Furth and Schwarz, Pfluger's Archiv, 1909. 129, 525.

2 Dodge and Benedict, " Psychological Effects of Alcohol." Washington, 1915.

The depression caused by alcohol in all the foregoing instances indicates a specific lowering of the powers of the lower nervous centres, similar to that produced by drugs like chloroform, though of much less intensity.

Voluntary movements, as distinct from reflex actions, are much more complex matters for investigation. Experiments have, however, been made which, without attempting to analyse the willed act, and accepting the movement made as index of that act's success, indicate how its efficiency changes with varying conditions. For example, the ergograph can be used to examine the power of a muscular act and its ability to withstand fatigue. In one form of this instrument the middle finger is commonly used to raise a weight by means of a string and pulley. The finger is fitted into a ring of leather, to which the string is attached; the weight is one of about 9 lb. The forearm and hand being at rest, this one finger is bent at intervals of from one to two seconds, the weight being lifted as high as possible. The movements are registered, and are kept up until exhaustion occurs.

Special caution, however, has been found necessary in interpreting the results obtained with the ergograph. The subject's mental conditions are liable to affect the records to a marked degree. Fleeting states of his mind, such as varying concentration of attention, and greater or lesser interest in the repetition of the movement at one time than at another, may distinctly influence the performance. The mere knowledge that he has or has not received a dose of alcohol may affect the subject's action, and thus obscure any effects produced by the alcohol itself.

Rivers,2 amongst others, has carried out investigations in which precautions have been taken definitely to guard against such sources of error. Experimenting upon two persons, he found that single doses of 5, 10, or 20 c.c. of alcohol left no indubitable traces upon muscular action, as recorded by the ergograph. With the dose increased to 40 c.c., a small increase in the number of contractions performed was shown by one of the subjects, who, previously, had been an abstainer from alcohol. The increase appeared about one and a half hours after administration of the dose. On the other hand, the second subject showed a slight decrease of work; but the investigator was not satisfied that this was a clearly-established effect due to the alcohol.

1 Dodge and Benedict, "Psychological Effects of Alcohol." Washington, 1915.

2 "Influence of Alcohol and other Drugs on Fatigue." London, 1907.

It was noted, however, that the 40 c.c. dose of alcohol did in one of the two subjects impair the execution of some skilled movements (adjusting the apparatus, etc.) incidental to the experiments, though not recorded on the ergograph. Also, within half an hour of taking the dose, "there came on a subjective feeling of lassitude and disinclination for activity, either of body or mind. It was doubtful how far the state of lassitude was preceded by one of exhilaration, but, if the latter occurred, it was certainly of very brief duration."

Oseretzkowsky and Kraepelin,1 giving a single dose of 50 c.c., likewise found no obvious effect of alcohol upon the ergographic record. Hellsten,2 using a form of ergograph in which the movement registered is executed with the two arms, and employing as the subject of the experiment an athlete of 90 kilos. weight, found similarly that single doses of 25 c.c. and of 50 c.c. of alcohol produced no clear and unequivocal effect on the record. The alcohol was given in appropriate dilution with water five to ten minutes before the test began. With a dose of 80 c.c., there was a slight and short increase in the recorded muscular work, followed by a marked decrease. When this dose was taken half an hour before the test began, the decrease observed amounted to 20 per cent. of the normal performance done without alcohol. When the alcohol was taken one hour previously, the decrease was 17 per cent., and when taken two hours before the test, 11 per cent.

The effect of alcohol on the muscular effort involved in walking uphill has been investigated by Durig.3 The conditions of the ascent - route, time of day, etc. - were kept as far as practicable the same for a number of successive tests, but on some days alcohol was added to the food ration, and on others it was omitted. The dose was 30 c.c. of alcohol in 150 of water, given at breakfast just before starting. It was found that although the walker, who was accustomed to moderate use of alcohol, felt in himself no difference between his condition on the alcohol days and on the non-alcohol days, the ascent per minute was on the alcohol days less by 12 to 14 per cent. than that on the non-alcohol days. This was so, although more energy was expended by his body on the former than on the latter days. The investigator was inclined to attribute this deterioration to impairment of the skill with which movements are directed: the effect of the alcohol tended to undo the results of previous training.

On a different scale, and of a different character, are the muscular movements involved in adjusting the eyballs to the focussing of the sight on an object brought closer and closer to the observer. The effects of alcohol on such movements have been studied by Guillery.1 He found that a dose of 20 c.c. did not affect the facility of adjustment, but one of 40 c.c. very distinctly weakened and slowed the movement. The impairment was first detectible about twenty minutes after taking the dose. Normal speed and power were regained about forty minutes later. A greater impairment was shown with 60 c.c. of alcohol; it came on sooner (in ten to fifteen minutes), and lasted longer (one and a half hours).

1 "Psycholog. Arbeiten," 1901, 3, [iv], 587

2 Skand. Arch. Physiol., 1904, 16, 160.

3 Pfiuger's Archiv, 1906, 113, 314.

Similarly, Dodge and Benedict found that a dose of 45 c.c. of alcohol measurably influenced the speed of starting the movement required in directing the gaze to a fresh object. Such a movement involves not only the motor centres directing the muscular action, but also the sensory nerve centres, information from which (as to the posture of the eyeballs and the direction in which they have to be turned) is a factor in the guidance and alertness of the motor centres themselves. The dose of 45 c.c. was found, an hour and a half after imbibition, to increase the normal delay in starting the movement by 15 per cent., taking the average for the six subjects tested. The same observers found also that a dose of 45 c.c. of alcohol reduced the rapidity of a simple to and fro finger movement by 88 per cent., taking the average for the same six persons as before. This test was likewise made one and a half hours after the alcohol was drunk.

Whilst, therefore, deductions must be cautious on account of the relatively small number of suitable experiments, the available evidence indicates that a single dose of less than 40 c.c. of alcohol has but little, if any, effect upon the performance of simple, " unskilled" muscular acts by an adult accustomed to moderate use of alcohol. On the other hand, the performance of acts requiring skill tends to be temporarily impaired by a dose of even 30 c.c, the effect being shown especially in a diminution of the speed and nicety of the performance. There seems to be no trustworthy evidence showing that, in normal circumstances, alcohol improves the efficiency of any muscular performance, skilled or unskilled.