THE COLOURLESS BLOOD-CORPUSCLES. 17 



As the corpuscles grow older and become more rigid, they, as it were, are caught 

 by the amoeboid cells. As cells containing blood-corpuscles are very rarely found 

 in the general circulation, one may assume that the occurrence of these cells within 

 the spleen, liver, and marrow of bone is favoured by the slowness of the circulation 

 in these organs (Quincke). 



Pathological- In certain pathological conditions, ferruginous substances 

 derived from the red blood-corpuscles are found in the spleen, in the marrow of 

 bone, and in the capillaries of the liver : (1.) When the disintegration of blood- 

 corpuscles is increased, as in ana?mia (Stahel). (2.) When the formation of red 

 blood-corpuscles from the old material is diminished. If the excretion from the 

 liver cells be prevented, iron accumulates within them ; it is also more abundant in 

 the blood-serum, and it may even accumulate in the secretory cells of the cortex of 

 the kidney and pancreas, in gland cells, and in the tissue elements of other organs 

 (Quincke). When the amount of blood is greatly increased (in dogs), after four 

 weeks an enormous number of granules containing iron occur in the leucocytes of 

 the liver capillaries, the cells of the spleen, bone-marrow, lymph-glands, the liver 

 cells, and the epithelium of the cortex of the kidney (Quincke). The iron reaction 

 in the two last situations occurs after the introduction of hemoglobin, or of salts 

 of iron into the blood (Glaeveck and v. Stark). 



When we reflect how rapidly (relatively) large quantities of blood 

 are replaced after haemorrhage and after menstruation, it is evident 

 that there must be a brisk manufactory somewhere. As to the number 

 of corpuscles which daily decay, we have in some measure an index 

 in the amount of bile-pigment and urine-pigment resulting from the 

 transformation of the liberated hemoglobin. 



9. The Colourless Corpuscles (Leucocytes). 



Blood, like many other tissues, contains a number of cells or cor- 

 puscles which reach it from without; the corpuscles vary somewhat 

 in form, and are called colourless or ivhitfi blood-corpuscles, or " leucocytes " 

 (Hewson, 1770). Similar corpuscles are found in lymph, adenoid 

 tissue, marrow of bone, as wandering cells or leucocytes, in connective 

 tissue, ami also between glandular and epithelial cells. They all con- 

 sist of more or less spherical masses of protoplasm, which is sticky, 

 highly refractile, soft, capable of movement, and devoid of an envelope 

 (Fig. 6). When they are quite fresh (A) it is difficult to detect the 

 nucleus, but after they have been shed for some time, or after the 

 addition of water (B), or acetic acid, the nucleus (which is usually 

 a compound one) appears ; acetic acid clears up the perinuclear proto- 

 plasm, and reveals the presence of the nuclei, of which the number 

 varies from one to four, although generally three are found. The 

 subsequent addition of magenta solution- stains the nuclei deeply. 

 Water makes the contents more turbid, and causes the cor- 

 puscles to swell up. One or more nucleoli may be present in the 

 nucleus. The corpuscles contain proteids, but they also contain fats, 

 lecithin, and salts (p. 37). The size of the corpuscles varies from four 



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