FIVE FIGURES
I n a previous paper it was shown that beginning with the first day of fasting the 0, consumption of the lung-fish falls in a regular manner for the first 200 or 300 days. From the available data it could not be told whether a constant metabolic rate is ultimately reached. The curve relating 0, consumption to time of fasting is for the early portion of the fast approximately logarithmic, and whereas the decrement in metabolism is apparent enough during the early portion of the fast, during the latter portion observations must be extended over a period of months or years in order to ascertain if the metabolic rate is continuing to fall, o r has reached a minimum level. There is not, however, any tendency to plateau within the first few months after the ingestion of food is stopped (Smith, '35). The general nature of this fasting curve has led us to examine more closely the effect of food upon the metabolic rate.
The lung-fish is essentially a carnivorous animal, subsisting under natural conditions upon molluscs and other invertebrates. I n captivity it thrives upon meat with occasional bits of liver, worms, etc. Once established in a balanced aquarium the animal eats voraciously and grows quickly, but we have found that when it is disturbed every day and confined to the smaller quarters such as we have necessarily used in our metabolic studies, it is difficult to get it to eat regularly, and 335