6 ARON. 



constant, the others, varying additional amounts so that a more or less 

 intensive growth results. The work must include a careful control of 

 the intake of food, of the body weight, and of the growth. Several 

 difficulties are encountered in determining the latter. It is obvious 

 that metabolism experiments are not suitable for this purpose, even if 

 the respiratory metabolism be included. Such experiments, if extended 

 over a long period, might reveal the total loss or gain of the body in 

 certain substances, but would give no information concerning the be- 

 havior of the different parts and organs. What we really wish to know 

 is the composition of the body at the beginning and at the end of the 

 experiment. 



A detailed analysis of the body appeals to me as the best method of 

 gaining this information. Of course, we can not analyze the same 

 animal twice. We can only determine its composition at the end of 

 the experiment, and in order to secure data concerning the probable 

 composition at the beginning we can either analyze a comparable control 

 animal or find the composition by calculation from data obtained on 

 other normal animals. 



My experiments have been confined to dogs. A medium-sized dog 

 is easy to handle, but large enough to permit a careful study and analysis 

 of the different parts and organs of the body with a fair degree of 

 accuracy. 



DESCRIPTION OF EXPERIMENTS. 



The general methods adopted were the following: 



The animals were placed in a quarantine stable for from one to four weeks 

 and the intestinal parasites, with which practically every dog in the Philippine 

 Islands is infested, removed.^" To this end, I gave from 0.5 to 1 gram of thymol by 

 mouth daily for a period of from seven to ten days. Following this the dogs were 

 allowed to become accustomed to their food and were all brought into a similar 

 condition as to nutrition. 



After this preparatory treatment, the animals were transferred to the experi- 

 mental stable. This was a large, airy room constructed under an old wooden 

 building with a wire fence on one side." Four to six animals had at least 

 20 square meters of space and were fairly well protected from the sun and rain. 

 Once or twice in the typhoon season they experienced a good drenching. The 

 floor of the stable was nearly 2 meters above the ground and was constructed 

 of small parallel boards with intervening spaces of about 1 centimeter to 

 allow water to flow away easily. The room was cleaned every morning by flood- 

 ing and once or twice each week it was disinfected with carbolic acid. 



" It has not been proved that parasites influence the metabolism in a marked 

 degree^ but in other experiments dogs on a low diet became emaciated and died 

 and their intestines contained numerous ascarides and tseniee. I am inclined to 

 believe that weak, poorly nourished animals suffer from these parasites. 



"Only two dogs (A and B) which were kept considerably longer, since Sep- 

 tember, 1910, were placed in large metabolism cages in the animal house of the 

 new laboratory building. 



