AN EXPERIMENTAL ANALYSIS OF OEDEMA IN 



THE FROG, WITH ESPECIAL REFERENCE TO 



THE OEDEMA IN RED-LEG DISEASE 



The determination of the causation of oedema, which is 

 associated with such a variety of pathological conditions, 

 would appear to be a highly complex problem. Attempts 

 have been made to show that there is but one primary cause 

 which accounts for its presence whenever and however it 

 manifests itself; on the other hand, there have not been a 

 few investigators who have claimed that it is due, not to a 

 single cause, but to a number of causes. 



Oedema is denned as the excessive accumulation of lymph 

 in the tissues and cavities of the body. When the excess of 

 lymph is generally distributed throughout the body, we speak 

 of a generalized oedema ; when the excess is confined to a 

 single locality or organ, the oedema is localized. The amount 

 of lymph in the tissues of an animal may at different times 

 vary considerably; it is onlv when the accumulation is clearly 

 greater than normal that we have an oedematous, or patho- 

 logical condition. To the attainment of this, water is essen- 

 tial. On account of the habits of the frog, and the free and 

 continuous passage of water through its integument, this 

 animal is a particularly favorable object for an experimental 

 study of oedema. 



Former investigations have given us, regarding the frog, 

 many facts pertinent to the present study. We know that 

 it is through osmosis (Maxwell, '13) that water is constantly 

 and continuously driven through the integument into the 

 subcutaneous lymph sinuses (Volhard, '12), and that at 

 high temperatures it is driven through more rapidly than 

 at low. We know also that when the normal frog remains in 

 water at a temperature within the range of that of its natural 



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