In the spring of the present year, Dr. R. W. Amidon, of New York, published a series of experiments entitled, “The Effect of Willed Muscular Movements on the Temperature of the Head: New Study of Cerebral Cortical Localisation.” * By these experiments the author sought to prove, not only that willed muscular movements cause elevations of temperature at the surface of the head, sufficiently marked to be capable of detection with thermometers, but also, that the contractions of different muscles affect the temperatures of different well-defined areas of the integument of the head; each muscle -according to him-having a special thermal centre in the cortical substance of the brain, the temperature of which centre is increased, when the muscle acts, in a degree suffi. cient—both absolutely, and relatively to the rest of the cerebral surface—to produce a change of temperature, in a circumscribed area of the overlying integument, appreciable by means of instruments of no great delicacy. Thus contraction of the quadriceps extensor cruris of one side caused an average rise of 0.409° C., on the opposite side of the head,

* Prize Essay of the Alumni Association of the College of Physicians and Surgeons of New York, March 12th, 1880; published in ‘Archives of Medicine,' April, 1880; also published separately by G. P. Putnam's Sons, New York.

in a space commencing 300 mm. behind the root of the nose, and extending backwards, on the median line, 80 mm., and laterally, from the same line, 50 mm.,—the extremes of rise of temperature being 1.388° C., and 0.1388° C.;* while contraction of the orbicularis palpebrarum of one side produced a rise averaging 0•342° C. (the extremes were 0.833° C., and 0.1388° C.), on the opposite side of the head, in a space situated about 100 mm. above, and a little to the rear of the external auditory meatus, and having a diameter of about 18 mm.

Dr. Amidon's method of procedure was as follows:-A number of thermometers (Seguin's surface thermometer, as improved by Dr. Gray, of Brooklyn, was employed) were placed at different points on the head, and secured to the latter by means of a quadrilateral piece of sheet rubber with straps and buckles at the corners, the rubber being pierced with holes for the passage of the stems of the instruments.

After ten or fifteen minutes of quiet, the readings of the thermometers were taken, and the subject then commenced to make vigorous contractions of some particular muscle or group of muscles (tonic and clonic spasms alternating produced the best results) for from five to ten minutes. At the end of five minutes from the cessation of the contractions the readings of the thermometers were again noted. marked rise of temperature is noticed in any one of them, the other thermometers must be brought together and concentrated about this spot so as to define the area over which the rise of temperature takes place as narrowly as possible.” Proceeding in this way, Dr. Amidon mapped out some twenty-five districts on the surface of the head, as thermal centres of a corresponding number of muscles or groups of muscles.

As long ago as 1866-67, one of the writers of the present paper (Lombard), while experimenting with thermo-electric apparatus on the influence of different mental states on the human temperature, was led to try the effect of muscular contraction on the temperature of the head. In doing this

* Dr. Amidon's values are given in Fahrenheit degrees, hence the extended decimals given above and in other places.

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he had no idea of a production of heat in the brain, specially connected with the muscular contraction per 8e; the muscular effort was made use of simply as a means of strongly fixing the attention. In the majority of these cases effect was produced ; but in a few instances, slight rises of temperature were noted-0005° C. to 0·02° C. It was found, moreover, that simply holding up a finger between the eye and an object regarded intently, at a little distance, and moving the finger at regular intervals to one side and back again, so as, in turn, to cover and uncover the object-pains being taken to move the finger to the same distance each time, and to accurately cover the object at each return-was more effective in causing a rise of temperature in the head, than strong contractions of the muscles of the arm or of the leg. At a more recent date (1877) the same person having occasion, in further experiments on the influence of mental activity on the temperature of the head, to study the effect of composition, thought it desirable to eliminate any possible disturbance arising from the muscular action concerned in the writing. It was found, however, that the mere mechanical movements of the pen were without effect.

In the investigations now to be given all the essential experimental details laid down by Dr. Amidon have been carefully observed; thermo-electric apparatus, however, has been substituted for thermometers, both as being far more sensitive, and also as enabling the observer to detect the slightest variation of temperature at any moment of the experiment. The particular apparatus employed has been fully described elsewhere.*

In the experiments "zero" denotes the temperature of the head at the commencement of the observations, and the “plus” and “minus” signs denote, respectively, rises above, and falls below this initial point. Where the words “stopped contractions” occur, they refer to the time immediately preceding them; for example, in 1st experiment on contraction of extensors of leg, &c., the contractions were stopped at the end of the tenth minute.

Other words put * J. S. Lombard, 'Experimental Researches on the Regional Temperature of the Head, London, 1879. Idem, ' Archives de Physiologie Normale et Pathologique,' July-August, 1868, t. i, p. 498.


in the margin refer to the times opposite to which they are placed. The experiments were all made on the writers themselves.

Experiments on the contraction (simultaneously) of the extensor

muscles of the leg and of the toes (quadriceps extensor cruris ; and the extensors proper of the toes), and of the flexors of the tarsus upon the leg (tibialis anticus, and peroneus tertius). The thermo-pile was applied at points varying from 310mm’s. to 370 mm's. distance from the root of the nose, measured on the median line, and from 10 mm's. to 40 mm's. distance laterally from the same line. The pile was on the left side of the head, and the muscles of the right side were contracted.

1st Experiment.
1° deflection of galvanometer is equal to 0.004166°C.

Rise or fall of temperature.
Time from
commencement Deflections of Thermometric
of contractions. galvanometer. values.


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In the above experiment, the temperature, at the end of the third minute succeeding the commencement of the contractions, had fallen 0·0208° C. below the starting point. During the remaining seven minutes of contractions it fluctuated between 0.0416° C., and 0.0124° C., both values being below the initial temperature. After the cessation of the contractions, the temperature fell still lower, being 0.2083° C. below the starting point, at the fourth minute,

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