THE FLUIDS OF THE BODY 81 



to accuracy how long they last, but probably their average 

 duration is comparatively short. The spleen is a labyrinth 

 of tissue-spaces through which at frequent intervals all red 

 corpuscles float. If they are clean, firm, resilient, they pass 

 through without interference. If obsolete they are broken 

 up. In the recesses of the spleen-pulp, leucocytes overtake 

 the laggards of the blood-fleet, attach their pseudopodia to 



FIG. 5. A MINUTE PORTION OF THE PULP OP THE SPLEEN, VERY HIGHLY MAGNIFIED. 



Stellate connective-tissue cells form spaces containing red blood-corpuscles and leucocytes. 

 In the centre of the diagram is shown the mode of origin of a venule. It contains two 

 phagocytes the upper with a nucleus, two blood-corpuscles just ingested, and one 

 partially digested in its body-substance ; the lower with two blood-corpuscles. 



them, draw them into their body-substance, digest them. 

 The albuminous constituent of haemoglobin they use, pre- 

 sumably, for their own nutrition. The iron-containing colour- 

 ing matter they decompose, and excrete in two parts ; the 

 iron (perhaps combined with protein) ; the colouring matter, 

 without iron, as the pigment, or an antecedent of the pigment, 

 which the liver will excrete in bile. Haemoglobin is un- 



6 



