The Exchange of Lipids Between Plasma and Lymph of Animals

The protein and lipid composition of dog, cat, rabbit and rat lymph collected from various ducts were studied by zone electrophoresis and chemical analysis. 2. All the protein and lipoprotein fractions present in the plasma could be identified in the lymph, but were present in lower concentrations. The plasma‐lymph gradients for proteins and for lipids were similar, and were greater in the cervical duct lymph than in the thoracic duct lymph. 3. During fat absorption, the large increments of fat appearing in the thoracic duct lymph could be removed by high‐speed centrifugation (20,000 g) without significant alteration to the post‐absorptive lymph protein and lipoprotein electrophoretic patterns. 4. The possible ways in which this particulate fat, which enters the blood stream from the thoracic duct during fat absorption, escapes from the circulation have been discussed. The finding that the lymph from the cervical and leg ducts contains some chylomicrons which are greater in number during alimentary lipæmia suggests that some chylomicrons may escape through the capillary membrane without degradation to smaller lipid‐protein complexes.