3158. Circulatory and lymphatic systems. 17 Color Photomicrographs. 1. Heart of snail, t.s. 2. Vein of mammal, t.s. elastic fibres 3. Artery of mammal, t.s. elastic fibres 4. Artery and vein, t.s. routine stained 5. Human blood smear, high magnification 6