AN EXPERIMENTAL ANALYSIS OF OEDEMA 



as in all other vertebrates. In the frog, however, oedema 

 manifests itself in yet another form. 



When the water is driven by osmosis through the integu- 

 ment of the frog into the subcutaneous lymph sinuses, it 

 there mixes with the lymph already present, received from 

 the tissue spaces, and with the chyle received from the intes- 

 tinal lymphatics. Through the lymph hearts the lymph thus 

 formed finally reaches the blood-vascular system, where it 

 mixes with the blood plasma. When for any reason more 

 water enters the subcutaneous lymph sinuses than can be 

 simultaneously excreted by the kidneys, free lymph will ac- 

 cumulate in excess of normal in these sinuses. In the frog 

 the subcutaneous oedema is always accompanied by the intra- 

 cellular (interstitial!) form, and vice versa. The problem 

 before us is the determination of the factors which in each 

 instance account for the gradual accumulation of lymph in 

 the body — that is, for the oedematous condition. 



Let us first consider those factors which might account for 

 the subcutaneous oedema already described. 



Experiments previously made by the writer in 1919 have 

 shown that the generalized oedematous condition of the body 

 observed in certain young frog larvae developed under ex- 

 perimental conditions, resulted from a deficiency in develop- 

 ment of the kidneys (pronephroi), which, therefore, were 

 unable, within a given time, to excrete as much water as 

 simultaneously entered the body through the integument. 

 The result was that lymph, in excess of normal, accumulated 

 in the body. The investigations of Howland ('16), and espe- 

 cially those of Swingle ('19), bear out these results in a 

 most striking manner, by showing that an oedematous condi- 

 tion of the body invariably results in young amphibian larvae 

 after the kidneys (pronephroi) have been extirpated. 



It has also been demonstrated by the writer ('19) that 

 when the ureters of adult frogs and toads have been ligated 

 and the animals remain in water, a general oedematous con- 

 dition of the body gradually develops and, as shown in table 1, 

 the rate at which lymph then accumulates in the body is 



