OBSERVATIONS BY HASSELBALCH. 19 



tion chamber, after at least 12 to 15 minutes or longer, according to circumstances. The 

 atmospheric air is analyzed either on the day of the experiment, or, in case of evening 

 and night experiments, the following morning. (The occasionally rather insignificant vari- 

 ations in the composition of the atmosphere during the experiments is without influence 

 on the results, so that now and then an atmospheric analysis is omitted. I have then made 

 my calculations, using the preceding day's analysis.) From the percentage composition of 

 the air before and after it passes into the chamber the respiratory quotient is estimated 

 (with a small reduction based on the supposition that the nitrogen does not take part in the 

 respiratory exchange) and from the quantity of air which has circulated in the respiration 

 chamber during the experiment and which has been determined by the gas-meter, the abso- 

 lute amount of the metabolism is calculated, with a reduction for pressure and temperature. 



The temperature during the experiment as recorded by a thermometer inside the respira- 

 tion chamber, fastened firmly to the under side of the glass top or ceiling of the chamber, 

 varies during the experiment between 31 and 35 C. The intention was to supply perfect 

 physiological conditions for the infants. Since, as a rule, they had been submitted to the 

 customary bath and had a particularly low temperature previous to the experiment, the body 

 temperature rose sometimes several degrees, but never above normal. This rise in tempera- 

 ture occurred almost entirely during the 15 minutes that preceded the experiment proper, 

 so that the temperature of the child (see in tables the last figures under " Body temperature") 

 can be considered as nearly constant during the experiment. 



The degree of humidity in the air is also physiological, since the inspired air, saturated 

 with moisture at the temperature of the gas-meter (15 to 20 C.), is afterwards warmed to 

 about 32 C. before it is inspired. The duration of an experiment is from 22 to 24 minutes 

 for each single determination. As regards the accuracy of the method, even if the greatest 

 possible errors in analyses are made (according to numerous double determinations of the 

 atmospheric air), this could alter the respiratory quotient only 1 or 2 in the third decimal 

 place. The weights of the children can not be counted on to give a greater accuracy than 

 =^=25 grams; partly for this reason and partly because the limit of error for the reading of the 

 gas-meter is =*=Q.5 per cent, the error in the determination of the amount of the metabolism 

 per kilogram of body-weight and per hour may be counted as ^2 per cent of the reported 

 value. 



When we consider that the respiratory quotient of the guinea-pig 

 embryo is about 1.0, even when that of the mother animal is consider- 

 ably lower, it is natural to expect that the new-born infant, which is 

 born with a greater or less store of glycogen in its liver, would live exclu- 

 sively at the expense of this supply in the first hours of its life and 

 accordingly give a carbohydrate quotient. This should be all the more 

 true, the shorter the interval between the birth of the child and the 

 beginning of the experiment. 



From table 1, in which 6 respiration experiments with new-born 

 infants weighing over 3,000 grams are arranged chronologically, it is 

 evident that the relationship is not quite so simple. The youngest 

 infant, which was 45 minutes old at the beginning of the experiment, 

 and one of the two oldest, which was 2 hours old, show quotients of 

 approximately 1.0, but in experiments 3, 8, and 7 a mixed exchange 

 takes place, in which carbohydrates are chiefly concerned; in experi- 

 ment 12 we find a pure albumin quotient, which can also originate from 

 the burning of much fat and few carbohydrates. 



If we now examine table 1 more closely, we see quickly that the sub- 

 ject of experiment 2, with a pure carbohydrate quotient, is recorded as 

 "fat and strong"; its weight is also striking in comparison with its 

 length (3,650 grams to 51 cm.). Although in experiment 9 no general 

 impressions of the infant's condition are recorded, it is obvious from the 

 weight and height that this was also a particularly well-nourished 



