

CONTENTS. 



PAGE 



I. Introduction 



1. Morphology of the vascular system, the angioblast 1 



2. Morphology of the lymphatic system 4 



II. Historical 4 



1. Vasa serosa 4 



2. Lymphatics with open mouths 4 



3. Discovery of endothelium G 



III. Embryology 7 



1. Introduction 7 



2. Lymphatics as dilated tissue spaces 8 



3. Analysis of Budge's work 8 



4. Statement of the three arguments for the origin of lymphat- 



ics from the veins 10 



A. Growth of lymphatic capillaries by sprouting 10 



B. Lymphatic and non-lymphatic zones 18 



C. Direct budding of the lymphatic vessels from the 



veins 21 



IV. Primary lymphatic system in different forms 24 



1. Primary lymphatic sacs in the pig 24 



A. General summary of the sacs 24 



B. Origin of the jugular sacs 25 



C. Origin of the renal sacs 35 



a. The retroperitoneal sac 35 



b. The iliac sacs 36 



c. The cisterna chyli 36 



D. The thoracic duct 40 



2. Primary lymphatic sacs in human embryos 45 



3. Primary lymphatic sacs in rabbit embryos 47 



4. Primary lymphatic sacs in cat embryos 48 



5. Primary lymphatic system in birds, posterior lymph heart 



and jugular lymph sac 50 



6. Primary lymphatic system in amphibia, anterior and poster- 



ior lymph hearts 55 



V. Peripheral lymphatic system .59 



1. In the pig 59 



A. From the jugular sacs 59 



B. From the renal sacs 63 



2. In other forms 65 



VI. Origin and development of lymphatic glands and their relation 



to primary lymph sacs 65 



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