xv i LIST OF ILLUSTEATIONS 



203. Semi-diagrammatic illustration of dividing small branch of pul- 

 monary artery of guinea-pig . . . . . . .183 



204. The capillary network connecting an arteriole and venule of the 



omentum of a young rabbit ....... 185 



205. Capillary vessel of the frog's mesentery ..... 185 



206. Two sinusoidal vessels from the medulla of the human adrenal . 186 



207. Precapillary venule and arteriole ...... 187 



208. Transection of an arteriole and venule . . . . .188 



209. Transection of the wall of the human vena cava . . . 189 



210. A 13 mm. human embryo ....... 192 



211. 'Vasoformative' cells from the mesentery of a rabbit seven days old 193 



212. The parietal layer of the pericardium of a child .... 196 



213. The endocardium 197 



214. Radial sections of the mitral valve, from the heart of a man . . 198 

 215. Human heart, opened from the right to show the atrioventricular 



bundle of His .199 



216. Reconstruction of the sino ventricular system (bundle of His) of 



the calf's heart 200 



217. Oxalated plasma of human blood clotted with thrombin, showing 



fibrin needles ......... 204 



218. From a freshly prepared, unstained specimen of human blood . 205 



219. Blood cells from a specimen of freshly drawn unstained human blood 206 



220. Showing the action of water upon the red blood corpuscle . . 206 



221. Five nucleated red cells (erythrocytes) from the blood of a frog . 207 

 222. Three nucleated red blood cells (erythrocytes) from the marrow of a 



human rib 207 



223. A group of cells from normal human blood .... 208 



224. A group of blood platelets, from the human blood . . . 209 

 225. Outline drawings of living polymorphonuclear leukocytes of rabbit, 

 from a drop of blood mixed with Ringer's solution to which a 



small amount of hirudin had been added to prevent coagulation . 211 

 226. Section of bone marrow from skull of 25 mm. turtle embryo (Chely- 



dra serpentina), showing three main stages in the hemopoiesis . 212 



227. Hemoglobin crystals 213 



228. Crystals of chlorid of hematin or hemin 213 



229. Wall of yolk sac of a 13 mm. human embryo (Fig. 210), showing a 

 small blood island and several small blood vessels contain- 

 ing erythrocytes 215 



230. Large blood island from yolk sac of a 13 mm. human embryo . 216 

 231. Diagrammatic illustrations of successive stages in the transforma- 

 tion of the mammalian erythrocyte to form the erythroplastid . 218 

 232. Successive stages in the elimination of the erythroblast nucleus, 



from homoplastic cultures of blood of a 32 mm. pig embryo . 218 



