NUTRITION AND GROWTH: I. 9 



rately before the rest were cooked. Heiiee it was only necessaiy to weigh the 

 cooked bones which corresponded to those previously set aside and add this 

 weight to the total in order to obtain the weight of the entire cooked skeleton. 

 A slight error is involved in this process because the extract of the cooked bones 

 is left with the meat. Another difficulty arises in the attempt to calculate the 

 water content of the fresh meat and the fresh skeleton. We know the total solids 

 in the skeleton and in the meat of the body; in the fresh stage we know only 

 their weight taken together. I have assumed the percentage water-content of the 

 freshly separated bones to be the same as that of the entire skeletal system. 

 These values are sufficiently correct to give a clear picture of the differences in 

 the relative proportions. I did not endeavor in these experiments to determine 

 the composition of the whole bodj', but tried simply to illustrate the most striking 

 differences. 



In the determination of total solids, ash, and nitrogen (Kjeldahl) the usual 

 methods were employed; in that of fat I used the method described of Baur & 

 Barschall." This procedure, which consists in the destruction of the nonfatty 

 material by sulphuric acid and the extraction of the fat by shaking the solution 

 so obtained two or three times with ether, is short and simple and gives as 

 satisfactory results as the Soxhlet method. It is especially applicable in the 

 Tropics, because during the greater part of the year the tap-water is so warm 

 that it becomes necessary to use ice-water in the condensers to avoid losing too 

 much ether. 



Experiment No. 1. — Four dogs of one litter were used in experiment 

 one. These were about two months old and all very much alike in 

 appearance. In the beginning I had intended to study the influence both 

 of different quantities and of different kinds of food upon growth and 

 so gave meat only to two animals, and carbohydrates as well as meat 

 to the other two. 



Two of the four dogs were fed so that their weight increased rapidly 

 (I and TV, Table 14), two were poorly nourished (II and III, Table 

 14). This experiment did not progress smoothly. The composition of 

 the food was changed several times. From the sixteenth to the twentieth 

 day, animals I, II, and III suffered from diarrhoea from some unknown 

 cause. From this period until the fifty-sixth day no accident occurred. 

 On the fifty-sixth day the native laboratory servant, who had been in- 

 structed to clean the stable with dilute carbolic acid solution, sprinkled 

 pure phenol not only on the floor, but also on the dogs, and burned num- 

 bers I, II, and III so severely that they were promptly killed with ether 

 to end their suffering. Number I escaped with only slight injuries. 

 He was kept until the 8th of April, when he developed cramps and 

 died in a few hours, apparently from internal injuries received from 

 a fall. 



During the relatively short period of this experiment animals I and 

 IV increased in weight from about 1,400 to more than 3,000 grams. 



"Ar&. a. d. kais. Gesndhtsmte. (1909), 30, 55-62. 



