IOWA ACADEMY OF SCIENCES. 33 



a bad scare, they may remaiu below the surface for twenty minutes or more, 

 and in a glass can, where they are able to watch all movements around them, 

 they may stay under water for more than thirty minutes without any move- 

 ments being made intended to scai'e them. How long they can be forced to 

 stay under water without drowning, when not in the hibernating state, was 

 not experimented upon. 



Caged frogs, left in a moderately warm place, about twenty degrees C, 

 seldom move unless disturbed, but when disturbed are very active. As the 

 temperature is lowered they become less active. At from ten to five degrees 

 C, when confined in a vessel of water a frog will genei'allygo to the bottom, 

 and after scratching around for some time, stop its movements, remaining 

 entirely submerged, and respiring through the skin alone. It may rise to 

 the surface and re.spire several times before finally settling down. At about 

 two or three degrees C, frogs seem to become unea.sy, slowly stretching 

 their legs and attempting to crowd themselves further down. This contin- 

 ues for some time after zero is reached, at which temperature they are quite 

 restless. 



At any time down to this point activity can be restored by gradual warm- 

 ing, and after torpor has set in, complete activity can be restored only by 

 heat. In this condition of torpoi-, the muscles readily respond to stimuli 

 both electrical and mechanical, showing them to be quite irritable. After 

 repeatedly punching such a frog with a stick, it sh'ows its uneasiness for a 

 number of minutes, stretching its legs, spreading its toes, and even coming 

 to the surface for a few swallows of air. The eyes generally remain closed 

 most or all of the time while in this condition of torpor, but in some cases 

 they are not closed at all, although the frog is not disturbed by quick and 

 direct motions very near them. When the eyes are touched they respond 

 with a wink, commonly remaining closed thereafter. 



Two frogs were placed in a jar of water which was reduced in tempera- 

 ture to the freezing point seven different times. For the first three times 

 they responded much in the manner described, but the fourth time and 

 thereafter, one of them, after staying down for some time, arose to the sur- 

 face and respired just as the water began to freeze, continuing respiration 

 even while the ice was forming around him. On the seventh cooling both 

 came to the surface in the same manner. These actions, however, may 

 have been accidental. No delicate instruments could be obtained to experi- 

 ment on the difference in temperature of the frogs and the surrounding 

 water, but it was not great, as the thermometer used would show no change 

 when the bulb was placed immediately upon the body of one 



One frog was placed in a towel whei'e the temperature of the atmosphere 

 was two degrees below zero C. for six hours, and although in a perfect tor- 

 por was capable of slight movement on handling, and on warming regained 

 perfect activity. 



A frog kept in my room was one night subjected to a fall in temperature 

 that froze the water in which he sat sufficiently to inclose the principal part 

 of the head, all of the legs and the sides in ice. A little water remained, 

 bathing the under surface of the body, and the back, which was above the 

 surface of ihe ice, had a moist appearance. By carefully thawing this frog 

 out he lived and was kept for fully two months afterward, showing that the 

 vitality had not been greatly reduced. On going to the frog cage in the 

 o 



