AN EXPERIMENTAL ANALYSIS OF OEDEMA 23 



motic pressure existing in the tissues and in the lymph which 

 escapes through the capillary walls of the blood vessels into 

 the tissue spaces. 



It has occurred to the writer that these same principles 

 are active in the causation of the oedema which accompanies 

 a disease very common among frogs known as red-leg. To 

 this we shall now turn our attention. 



ON THE OEDEMA WHICH IN FROGS ACCOMPANIES RED-LEG DISEASE 



According to Emerson and Norris ('05), red-leg disease, 

 which is widely distributed throughout North America and 

 Europe, is due to the presence in the frog of Bacillus hydro- 

 philus fiscus. 3 They state that the predisposing causes of the 

 disease are lower resistance from heat, anemia, and lesions 

 of the skin, which seems to be the portal of entry of the infec- 

 tion. The symptoms which characterize the disease are con- 

 gestion of the ventral surface of the body and more or less 

 ulceration in and haemorrhage beneath the skin. In advanced 

 cases of red-leg, the abdominal viscera, and especially the 

 stomach and intestines, may become greatly congested, as 

 may also the muscles of the body in general. As the disease 

 progresses and congestion becomes more general, it may be 

 accompanied by more severe haemorrhages and by degenera- 

 tive changes in the tissues. The disease is usually fatal, and 

 a gradual failure to respond to stimuli is followed by coma 

 and death. The oedema which accompanies red-leg disease 

 may be either localized or generalized in character. It may 

 be confined to one or to both hind limbs, and either to the 

 entire limb or to the limb above or below the knee-joint. When 

 the oedema is generalized in character, the entire body, in- 

 cluding the limbs, may be generally and uniformly swollen. 



Figure 2 is a photograph of a frog with red-leg disease, in 

 which a rather intense form of localized subcutaneous oedema 

 of the right thigh has developed. Figure 3 also is a photo- 

 graph of a frog with red-leg disease, but here there is a local- 



3 Cultures were made by Mr. Vincent Gregg, who identified the bacillus men- 

 tioned. 



