The present sets of studies indicate that the fibrous capsule which encloses each tissue module divides the interstitial fluids into an intracapsular pool, and an extracapsular pool. Fluid that filters out of the capsules into the extracapsular clefts is the source of the lymph. Because of the limited permeability of the capsular barrier the composition of lymph differs from that of the capillary ultrafiltrate. Lymphatic vessels are means for the drainage of the extracapsular fluids and other

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... terials. This appraoch differentiates two entirely separate types of edema: an intracapsular dependent pitting edema and an extracapsular generalized non-pitting edema. Three sets of experiments that support the foregoing hypothesis are briefly presented.