SOME OBSERVATIONS ON THE DEFECATION OF THE BULL-FROG (Rana catesbeiana)

Abstract

In order to observe the frequency of the defecation as well as the form of the feces, bull-frogs (Rana catesbeiana) were fed once a day on fresh calf liver for 42 days from May through July in 1972. One group being fed on 5 g of liver, while the other one on 10 g of it. The temperature of the frog keeping room was kept at 20.5-31.3°C. The results obtained were as follows:(1) There were 1-4 compressions on the surface of the feces extruded in a short time after thecapture of animals. It may be presumed that the compressions are due to the tonic constriction rings produced on the large intestine at the moment of the defecation.(2) Among the former group the defecation interval of 12-24 hours ranked first (38.9%), and that of 24-36 hours came second (18.5%), that of 0-12 hours (17.1%) third, being followed by that of 36-48 hours (10 .9%); defecations (85.5%) for the most part thus occurred with intervals shorter than 48 hours . In the latter the intervals of defecations showed the tendency similar to that seen in the former .(3) When the animal defecated, it firstly set its hind legs slightly apart from each other, raising the coccyx a little, and the anus then swelled out to extrude the feces .When the extrusion of the feces was incomplete, the anus rhythmically repeated its swelling, the interval of which coincided with that of the large shortening contraction of the large intestine.