[cameron-brownlee] gas in TISSUES OF THE FROG 59 



or two per cent of oxygen, is also found in all the lymph spaces, and 

 distends all the body tissues. 



The amounts of liquid absorbed, shown in Table I, are all too 

 small by the amount actually absorbed in the tissues at the time of 

 measurement, and unmeasurable. The one occasion in which no 

 measurable liquid was found (No. 9) is probably therefore an extreme 

 case, and we feel justified in assuming that the absorption of gas 

 only takes place when liquid is being absorbed also. 



"Retention of gas" is probably a more accurate description of the 

 phenomenon. Up to the period at which swelling commences it must 

 be assumed that gas passes through the skin by diffusion, both oxygen 

 and nitrogen. This certainly takes place in one direction, inwards. 

 The oxygen is used up, and the carbon dioxide presumably excreted 

 through the skin. It cannot be definitely stated in what manner the 

 nitrogen is normally got rid of. It seems most probable that the 

 outward diffusion is as fast as that inwards. When swelling com- 

 mences, in most cases some change takes place, so that the nitrogen 

 can no longer be completely eliminated. If we assume that the oxy- 

 gen and nitrogen are absorbed in proportion to their partial pres- 

 sures, then it follows that a large part of the nitrogen is still got rid 

 of in some way ot other. For example, case No. 16, Table I, shows 

 that 22 • 5 c.c. of nitrogen were retained in 6 days by a frog whose orig- 

 inal weight can be taken (from the residual weight) as approximately 

 60 grams. This would correspond to an oxygen intake of only 4-5 

 c.c. during the same period, which corresponds to 0-5 c.c. per kilo- 

 gram per hour, a negligible figure compared with Krogh's results 

 already quoted, even when the marked inertia of the frogs in these 

 experiments is taken into account. 



If gas and liquid absorption is allowed to proceed, then the animal 

 becomes more and more lethargic, and finally dies, in a more or less 

 distended condition. The cause of death may be connected with 

 the physical distension, or with some change brought about chemically 

 by the considerable dilution of the lymph and resulting lowering of 

 the osmotic pressure of the body-fluids, or with both of these. If 

 the animal is removed from water at any period before death has 

 actually occurred, and allowed to remain in its normal moist atmos- 

 phere, then it becomes quite normal in three or four days. 



The amount of gas absorbed should theoretically be proportional 

 to the area through which absorption takes place (a function of the 

 weight) and the time during which absorption takes place (called 

 "Time of buoyancy", in Table I). There is no marked proportion- 

 ality to the former shown in the table. That to the latter is not 

 very distinctly shown. The figures are too few to prove any certain 



