66 THE ROYAL SOCIETY OF CANADA 



Speaking generally the observations in these experiments agree for 

 the most part with our own results, and bearing them in mind we con- 

 clude that the absorption of liquid which takes place at an uncertain 

 and varying interval after frogs are immersed in Winnipeg tap-water 

 is brought about by the solid constituents of the water acting on the 

 cells of the skin (as suggested by Durig) and permitting normal 

 osmosis to take place. While the possibility of absorption through 

 the alimentary tract must be borne in mind, we think that the balance 

 of the evidence is against this playing any large part in the total 

 absorption, since it is evident that the skin can allow the passage of 

 water in either direction and does so under suitable conditions, while, 

 as we have pointed out, the gas-retention observed in our experiments 

 seems to take place only when liquid is being absorbed, and the gas- 

 exchange almost certainly takes place through the skin. 



Although our own experiments with distilled water do not lend 

 support, we think it probable that in a water containing smaller 

 amounts of solid constituents than that which we had to employ, 

 the average life of frogs completely immersed would be much longer 

 than the sixteen days we have actually found. 



Further, although our experimental data are insufficient to warrant 

 more than the suggestion, we consider it probable that the gas retention 

 is due to some pharmacodynamic action of one or more of the constitu- 

 ents of the tap-water on the skin of the frog. 



Summary of Results. 



(1) Specimens of R. pipiens immersed in Winnipeg tap- water 

 during late winter and spring will live on the average sixteen days. 

 The extreme periods observed are 3 and 52 days. 



(2) The frogs remain perfectly normal for some time, but at a 

 variable period before death ensues — usually several days — they 

 commence to swell. The swelling is due in all cases to the absorption 

 of water, and in most cases this is accompanied by retention of absorbed 

 nitrogen. In such cases the frogs show marked buoyancy, and are 

 unable to dive away from the framework confining them below the 

 surface of the water. If the frogs are removed at any stage before 

 death occurs, they recover completely in a few days. If allowed to 

 remain, death ultimately takes place, and is presumably connected, 

 physically or chemically, with the distension. 



(3) The causes of the phenomena are discussed, and other 

 experiments described which throw some further light upon them. 



In conclusion we wish to thank Professor Swale Vincent for the 

 interest he has taken in the work throughout its course. 



