Popular Science Monthly/Volume 84/March 1914/The Effects of School Life Upon the Nutritive Processes, Health and the Composition of the Blood

Popular Science Monthly Volume 84 March 1914  (1914) 
The Effects of School Life Upon the Nutritive Processes, Health and the Composition of the Blood by Lewis Madison Terman




THE school is a formal agency devised for the purpose of bringing the child into possession of the main body of our social inheritance—the treasures of knowledge and skill laboriously accumulated by many generations of ancestors. When these treasures were few and pertained mostly to the affairs of immediate self-preservation, there was little danger of overburdening the young in the process of their acquisition. The intricacy of present-day civilization, however, is constantly increasing the difficulties which must be met and overcome by all who are not to become playthings of complex social and industrial forces. The period of infancy has not lengthened in proportion to the increased educational demands upon it. The school year has been considerably extended and for the first time in the world's history attendance has been made generally obligatory.

That this situation involves certain physical dangers to the child is self-evident. Indeed, the charge of school overpressure has been made repeatedly for at least half a century, though it is only recently that investigations of scientific character have been directed to the problem. Some of these are here reviewed, in the hope that further researches in this important field may be stimulated.

The Effects of School Life upon Growth

Schmid-Monnard sought to ascertain the influence of school life upon growth by comparing the growth attained during the seventh year of life by children in school with that attained by children of the same age who had not entered school. The results, as shown in the following table, indicate that school entrance constitutes a shock to the nervous system of the child severe enough to retard growth (15).

Growth in Weight
Expressed in Kg.
Growth in Height
Expressed in cm.
Boys Girls Boys Girls
Pupils not attending school 2.2 1.9 7.4 5.6
Pupils attending 1.5 1.6 4.2 4.5
Difference in favor of former .7 .3 3.2 1.1

Engelsperger and Ziegler (4) measured about 500 children, five to six years of age on entering school and again two months later, and found that 20 per cent, had lost weight. This appears significant in view of the fact that the early fall is normally the season of most rapid growth in weight. The retarding effect was most marked in the youngest pupils, those under six years of age. The authors conclude that entrance before the age of six years should not be permitted and that in many cases it ought to be postponed until seven or eight.

Quirsfeld (14) followed the growth of 1,014 children through the first four years of school life and found that 46 per cent, failed to gain weight during the entire first school year, while 21 per cent, showed an actual loss. The number failing to gain during the second year was only 10 per cent., the third year 8 per cent, and the fourth year about 6 per cent.

The Effects of Prolonged Mental Strain upon the Nutritional Processes and the Composition of the Blood

One of the evils most often blamed for school overpressure is the formal examination. In 1896, Serafani found that examinations caused a marked reduction in the amount of nourishment taken by university students, and a corresponding decrease of weight. His conclusion was to the effect that prolonged examinations tend to bring about a condition of the nervous system resembling that characteristic of persons who are chronically neurasthenic.

Ignatieff (8) made a study of the physical effects of examinations on 242 pupils, ten to sixteen years of age, in a Moscow military school. The pupils were weighed just before they began preparation for the examinations, again at the close of the examinations, and finally after the close of the ensuing 31/2 months of vacation. Comparing the second weighing with the first, Ignatieff found that 79 per cent, had lost weight, that about 11 per cent, had not changed and that only 10 per cent, had made any gain. Since the examination and the preparation for it extended over a period from one to two months, and since the pupils were at an age when growth from month to month is normally very rapid, all ought to have shown a gain. As it was, those of the lowest grade lost on an average 2 per cent, of their weight and those of the highest classes over 3 per cent. Quite different is the result when we compare the weight records before vacation with those after vacation, for here we find loss of weight with only 4.6 per cent, and gain with 90 per cent. For 13 pupils, however, the extended vacation was not sufficient to make up the loss of weight suffered during the strenuous pre-vacation period. Ignatieff concludes that in its physical effects the examination is comparable to a severe illness, and that a mental strain severe enough to cause such profound alterations in metabolism could hardly fail to affect unfavorably that organ most concerned in the overpressure—the brain itself.

Binet and Schuyten (2), by carefully weighing the quantities of food consumed by school children in the different months of the school year have been able to show that the child's appetite deteriorates as the school year proceeds. The exact causes of such deterioration are very complex and difficult to disentangle, but the basis, at least, for an explanation is to be found in such investigations as those of W. B. Cannon, Pavlow and others on the physiology of digestion.

Data of this kind lead us to infer that the nervous stimulation involved in excessive mental work produces its injury through such reflex effects as those upon the nutritive processes. Graziani, however, has raised the question whether in addition there may not be unfavorable influences more direct than this explanation assumes. He believes there are two such influences: (a) Imperfect oxygenation of the blood and incomplete elimination of carbon dioxide due to the superficial respiration proved by Mosso, Macdonald, Bush, Obici and others to result from application to mental tasks; and (b) an immediate effect upon the chemical composition of the blood corpuscles due to the accumulation of fatigue products resulting from mental work (5).

In order to test the latter theory, Graziani subjected 18 university students and 17 children of ten to twelve years of age to blood tests before and after the preparatory period for school examinations. The tests involved three determinations: the number of red corpuscles, the relative proportion of hemoglobin which they contained, and their power of resistance. In regard to the number of corpuscles, no constant differences were found either with university students or with children. The proportion of hemoglobin, however, showed a decided decrease, amounting to an average of 10 per cent, with the students and to nearly that much with the children. The effect upon the power of resistance of the red corpuscles was much the same as other investigators had shown to result from certain poisons. Graziani, therefore, concludes that in all probability mental work produces a toxin which brings about an immediate change in the chemical and functional properties of the blood.

To try this theory still further he subjected himself and a twelve-year-old boy to the same kind of blood examinations, except that in this experiment the blood tests were separated only by a number of hours of strenuous mental work instead of by many weeks, as was the case in the earlier experiment. Here, again, the decrease of homoglobin was marked, amounting on an average to 7.5 per cent, with Graziani himself and to 8 per cent, with the boy. Graziani believes that the underlying cause of school anemia, with its alterations of metabolism and its imperfect oxygenation of the blood, is to be sought in the influence of excessive accumulations of toxic products of fatigue.

Another important study of this type by Helwig (6) corroborates the findings of Graziani. This author made many blood tests upon himself and six other subjects for the purpose of determining the influence of school work, fresh air, rest, marches and lessons of different degrees of difficulty both upon the number of red corpuscles and upon their "degenerative" and "regenerative" processes. The study seems to have been made with the most approved technique and with the greatest regard for scientific accuracy.

The results were rather variable for the corpuscle count, but quite striking as regards the "degenerative" and "regenerative" processes.

As a result of school work the "disintegration-quotient" was increased 29 out of 33 times. The author holds that the study "distinctly" demonstrates that school work not only imposes a strain upon the nervous system, but that it produces a "destructive effect on the blood corpuscles." The numerous tables presented by the author show rather convincingly the influence of the following factors in determining the total condition: (a) the difficulty of the school work; (b) the length of the work period; (c) the frequency of the recitation intervals; (d) the amount of exercise and the access to fresh air.

Arduous mental work produces destructive changes in the blood, while recuperation causes the elimination of waste products and finally a more or less active regeneration of corpuscles.

Observation of the children also showed that external manifestations of fatigue invariably accompany the microscopical phenomena associated with this state.

It was not only from highly sensitive children that these reactions were obtained. The author observed the same phenomena in his own person after long-continued mental strain.

While a considerable degree of disintegration could be noted in the morning after several weeks of concentrated sedentary work indoors, accompanied by physical depression, lassitude and heaviness, this phenomenon disappeared, together with the subjective symptoms, after a walk of two hours. On another occasion the disintegration quotient increased considerably after four hours incessant work at the microscope prior to taking food and following a prolonged period of close application to research work, but decreased rapidly after two hours devotion to a totally different occupation and lunch taken in the open air.

Rest days showed an immediate effect in a lower disintegration quotient. Long and tiring marches produced only small degenerative values and were followed by rapid regeneration. During a day of mental work disintegration continually increases until late in the afternoon, indicating that this part of the day is least suitable for hard study.

The reverse phenomenon, the improvement which takes place in the composition of the blood as the result of a well-spent summer vacation, has been dealt with experimentally by Borchmann and others (3). Borchmann gave blood tests to 19 boys and 18 girls of Moscow before a two months' "summer colony" outing, and again after their return. The second test revealed an average gain of nearly a million red corpuscles per cubic millimeter of blood and a marked increase of hemoglobin. This is set forth in the following table:

Boys. Girls.
Red Corpuscles per Cubic Min Red Corpuscles per Cubic Mm.
Percentage of Hemoglobin Percentage of Hemoglobin
Before vacation 3,884,000 73.1 3,760,000 69.6
After vacation 4,820,000 79.2 4,480,000 78.3

Borchmann also tested eight of the girls two months after their return to school and found that in three the number of red corpuscles had still further increased about a quarter-million per cubic millimeter, while in the other five there was a decrease of about two thirds of a million as compared with the second count. But in no case was the condition as unfavorable as before the vacation. The hemoglobin had in some cases decreased 5 per cent, below the second showing, had increased in others, but in all cases it surpassed the pre-vacation record. Lauch had already secured similar results for children of Geneva, and the work of both is strikingly corroborated by numerous blood tests of children who have been transferred from unhygienic conditions of the ordinary class room to the Open Air School.

The Effects of School Postures on Respiration

The effect of school occupations on the respiration has been studied experimentally by Oker-Blom (13) and by Badaloni (1). The latter secured kymographic records showing the amount of respiration in the upper part of the lungs resulting from different postures assumed in writing. In this way it was determined that the asymmetrical position induced an inflexibility of the upper part of the chest and a decreased depth of respiration in the upper part of the lowered side. Later Binet raised the question whether this may not be compensated by simultaneously increased abdominal breathing. In a second study Badaloni was able to show that no such compensation takes place. His records prove that the asymmetrical position brings a "remarkable decrease" in the expanding capacity of the upper chest. The symmetrical sitting posture, even when the sternum was allowed to touch the desk, showed a far less injurious effect. The author concludes, therefore, that it is the asymmetrical position, rather than the sitting posture per se, which is responsible for the school's evil effects upon the lungs. He believes that the school is in this way an important cause of tuberculosis.

In 1911 Oker-Blom (13) reports a similar experimental study of respiration carried on with 25 pupils during different school occupations. The most marked difference found was that between the standing and the sitting respiration. The decrease in total respiration for brief sitting (3 minutes) was about 8 per cent., and for longer periods (12 to 39 minutes), 50 per cent. Interesting differences appeared with different kinds of school work. Knitting, for example, showed an impeding effect upon the respiration of the upper left lung 18 per cent, greater than did reading aloud. In agreement with the results of Badaloni, the greatest impediment to respiration was found in the upper part of the lowered side of the chest. This in turn aggravates the asymmetrical condition and helps to explain why scoliosis tends to run a progressive course. Oker-Blom concludes that all kinds of school activities, including hand-work, must be frequently alternated with change of position and with physical exercises if the danger of scoliosis is to be avoided.

The School as a Cause of Morbidity

Hertel's pioneer study (7) of the health conditions and work habits of 3,141 boys and 1,211 girls in the secondary schools of Denmark not only revealed what was then regarded as an incredible amount of physical defectiveness, but also demonstrated sufficient correlation of morbidity with years of school attendance and with daily hours of study to forcibly suggest a cause and effect relation. In the first two classes (children eight to ten years) 18.4 per cent, were suffering from one or more chronic defects serious enough to impair health. By the end of the third year the amount had risen to 34 per cent., and by the end of the eighth year, with its average of 81/2 hours of daily study, to nearly 50 per cent. Especially significant is the fact that the pupils whose studies were chiefly of scientific nature showed a decidedly lower per cent, of morbidity than obtained among the students of classical courses, which make heavier demands upon strictly intellectual application and afford less opportunity for physical activity. Conditions were even worse among the girls, among whom morbidity rose rapidly from about 30 per cent, in the first two grades to over 60 per cent, by the age of 12 to 16 years. It is difficult to avoid the suspicion that the daily period of study, which increased concomitantly from about seven to about nine hours, may have been to some extent causally related to the increase in morbidity.

The later study of Schmid-Monnard (15) of 5,100 boys and 3,200 girls in the secondary schools of Germany confirmed essentially all the findings of Hertel, revealing in the upper grades a marked increase in frequency of headaches, insomnia and other nervous symptoms.

Roughly speaking, schools with both morning and afternoon sessions showed in the higher grades nearly twice as much morbidity as schools with forenoon sessions only. This is shown in the following table.

Morning Session Only. Morning and Afternoon
Per Cent.
Per Cent.
Per Cent.
Per Cent
Total morbidity 25 39 50 74
Nervousness and headaches 13 28 25 62
Insomnia 1 .5 5 4 19

Both Hertel and Schmid-Monnard found that the percentage of morbidity rises considerably toward the end of the school year. Mortality, also, slightly increases for a brief period after school entrance, as does also the incidence of infectious diseases.

The most extensive and important single investigation of this kind yet made is that carried out by the Russian Department of Education, the results of which were reported by Khlopine in 1911 (10). This investigation was essentially a sanitary census of all the secondary schools of the Russian empire, carefully and uniformly carried out under the direction of the chief medical officer of schools, and including about 116,000 out of the 139,000 pupils enrolled. Its main purpose was to establish the incidence for age, grade, sex and type of school of the following defects: myopia, spinal curvature, nasal hemorrhages, headaches and nervous troubles.

Khlopine's data show that myopia is much more common in the upper grades than in the lower, in the larger cities than in the smaller, and in western than in eastern Russia. Spinal curvature increases about 50 per cent, between the first and the last school grade. Between the first and the seventh grade headaches double in frequency while nervous troubles increase nearly fivefold. Nasal hemorrhages, which are thought by some to be associated with the circulatory changes in the head which result from the act of reading, were twice as common in the classical schools, with their heavier demands for reading, as in the technical schools.

We can not here enter into a critical discussion of the above investigations. It is well to emphasize, however, that such studies have to deal with exceedingly complex factors whose respective influences are hard to separate. At the same time, the problems are very challenging to the biologist and physiologist as well as to the school hygienist, and are probably capable of being refined in such a way as to yield more positive results than we have yet had on this aspect of human efficiency.


1. Giuseppe Badaloni. Encore du travail a l'école en rapport a la fonction de la respiration. Inter. Mag. Sch. Hyg., 1910, VI., pp. 153-165 (cf. Volume II., 1906).
2. Binet. La Consommation du pain pendent une année scolaire. L'Année psych., IV, 337 (see also Schuyten, Paedolog. Jaarb., 1908).
3. Borchmann. Über den Einfluss der Ferienkolonien auf der Beschaffenheit des Blutes des Kindes. Zt. f. Schulges., 1899, pp. 320-323.
4. A. Engelsperger u. O. Ziegler. Beitr. zur Kenntniss der physisehen Natur des sechsjährigen in die Schule eintretenden Kindes. Zt. f. Exp. Päd., I., pp. 173-235, and II., pp. 49-95.
5. Dr. A. Graziani. Einfluss der übermässigen Geistesarbeit auf d. Zahl. Hämoglobingehalt u. auf den Widerstand der roten Blutkörperchen. Zt. f. Schulges., 1907, pp. 337-353.
6. Dr. Helwig. Neure Untersuchungen ü. d. Wirkung des Unterrichts auf den kindlichen Körper. Inter. Mag. Sch. Hyg., 1911, pp. 216-224.
7. Hertel. Overpressure in the High Schools of Denmark. London, 1885.
8. Ignatieff. Der Einfluss der Examina auf das Körpergewicht. Zt. f. Schulges., 1898, p. 244.
9. Mlle. Ioteyko. Le surmenage scolaire. Rev. Psych., 1910, pp. 265-297.
10. G. W. Khlopine. Les maladies scolaire parmi les éleves des établissements d'enseignement moyen russes. Inter. Mag. Sch. Hyg., 1911, pp. 230-291, and 329-368.
11. Arthur MacDonald. Einfluss der Gehirnarbeit auf die Atmung der Schüler. Zt. f. Schulges., 1896.
12. Albert Mathieu. La question du surmenage scolaire. Inter. Mag. Sch. Hyg., IV., 1908, pp. 419-431.
13. Max Oker-Blom. Uber die Einfluss verschiedenartiger Schulbeschäftigung auf d. Ventilation der oberen Lungenteile. Inter. Mag. Sch. Hyg., 1911, pp. 369-405.
14. Dr. E. Quirsfeld. Zur physisehen u. geistigen Entwl. des Kindes während der ersten Schuljahre. Zt. f. Schulges., 1905, pp. 127-185.
15. Dr. Karl-Monnard. Die chronische Kränklichkeit in unseren mittleren u. höheren Schulen. Zt. f. Schulges., 1897, pp. 593-615, and 666-685.
16. Dr. M. Schuyten. Qu'est-ce que le surmenage? Rev. Psych., I., 1908, pp. 143-157.