I9I2] Paul E. Howe 91 



plete fast in which there is total abstinence from both food and 

 water; a modification of this, in which the subject is permitted to 

 take water "ad libitum" or caused to ingest a uniform quantity 

 from day to day ; and the incomplete fast, in which one or more of 

 the food principles or chemical elements contained therein is with- 

 held, such as a diet lacking in protein, fat, carbohydrate, water, salt 

 or certain amino acids. 



There is not a marked distinction between complete fasting 

 and fasting with water taken "ad libitum," for under the latter con- 

 ditions the quantity of water taken decreases as the fast progresses 

 until finally there is a natural abstinence from water. Some hold 

 that the desire for water returns just before death. The ingestion 

 of water causes a lengthening of the life of the animal and the 

 severity of the fast is lessened. If at any time the quantity of water 

 given is increased there will be for a time an increase in the metab- 

 olism (14). This condition also holds for the well nourished 

 animal (8), i. e., under all conditions when the water ingestion of 

 the animal is sufficiently increased the general metabolic processes 

 of the organism are stimulated. 



The length of a fast which would result in death depends upon 

 the size, the species, the age, the nutritive condition, the external 

 surroundings (e. g., temperature, humidity, etc.) and the intrinsic 

 rate of metabolism. In general, we may say that the smaller the 

 subject the shorter will be the time it can live without food; but this 

 does not hold in all cases, for certain of the lower animals can fast 

 much longer than the higher forms, e. g., the Salamander, which is 

 about 3-4 inches long, has been fasted for more than 125 days (19). 

 Adult organisms can fast longer than the young of the same species. 

 Thus, a young pup can fast but a few days, while a füll grown dog 

 will fast from 20 to 60 days. Of the fasts on man and other warm 

 blooded mammals, the longest on record is one of 117 days (15). 

 This experiment was conducted in our laboratory, a Scotch collie 

 dog being the subject. Subsequent to this long fasting interval the 

 dog was fed, and it returned to its normal condition. 



A comparison of the results obtained by various investigators 

 shows that death does not ensue until there is a loss of between 40- 

 50 per Cent, of the original body weight. The real cause of death 



