14 THE ROYAL SOCIETY OF CANADA 



consciousness supervenes, occurs within two or three hours, or not at 

 all. Somatic death occurs before the death of heart, brain, and 

 nervous system, and muscle. The actual cause of death has not been 

 ascertained. Similar results were obtained for R. clamita?is. Babâk 

 and Amerling's results with R. fusca and esculenta indicate that 

 considerable variations exist in different species in the resistance 

 offered to high temperatures. 



The same relationship between temperature and time of survival 

 exists for exsected muscle. At the lower temperatures (below 35°) 

 heat-rigor does not ensue. 



3. Specimens of R. pipiens completely immersed in Winnipeg 

 tap-water (a very hard water) during late winter and spring (1914-15) 

 lived on the average 16 days, the extremes noted being 3 and 52 days. 

 The frogs remained perfectly normal for some time, but at a variable 

 period before death ensued^ — -usually several days — ^they commenced 

 to swell. This was due in all cases to the absorption of water, which 

 in most cases was accompanied by retention of absorbed nitrogen 

 (dissolved in the tap-water) resulting in a degree of buoyancy which 

 tended to keep the frogs at the surface of the water. Such nitrogen 

 can be retained in large amounts, the maximum observed being in a 

 frog of initial weight 60.5 grams, which absorbed 16 grams of water, 

 and retained 22.5 cc. of gaseous nitrogen. 



If the frogs were removed from water at any stage before death 

 occurred they recovered completely in a few da^s. If allowed to 

 remain they ultimately died, death being presumably connected, 

 physically or chemically, with the distension. 



In the intervening years I have made a number of observations 

 bearing on the above and similar facts dealt with in these papers. 

 These will now be described briefly. 



Experiments at Maximal Temperatures. 

 Lord Lister states that frogs are killed by being held in the hand 

 for about a quarter of an hour. In an experiment with R. pipie^is 

 already described I found that breathing ceased after 10 minutes, ' 

 there were convulsive movements after 15 minutes, and the animal 

 was unconscious after 20 minutes, with rapid and strong heart-beat. 

 It recovered in 10 minutes. With this can be contrasted the following 

 observations : 



R. temporaria (South of England). August 13th, 1915. 



A full grown frog was held for 15 minutes in my hand. There were convulsive 

 struggles after 7 minutes. The animal was unconscious at the end of 15 minutes. 



