68 HIS TOL OGY OF NUTRIENT FL UJDS. 



thyroid and supra-renal glands, is chiefly concerned in blood 

 formation. The red bone marrow was first pointed out by 

 Neuman as a place where red globules were formed, and sub- 

 sequent research confirmed his observations. The giant cells 

 of the marrow (myeloplaxes), as well as of the spleen, liver 

 and lymph glands of the fcetus, have been seen to have a part 

 in blood formation. Ranvier has described such cells in the 

 omentum of young rabbits, and Heitzman in ossifying carti- 

 lage. It has even been proposed to call the giant cell angio- 

 blast. In fine, we may regard any particles of bioplasm swept 

 into the circulation as leucocytes, or white blood cells, and 

 chemical or structural changes transform them into red ones, 

 while many of the latter may have an independent origin. 



VIII. PATHOLOGICAL CHANGES IN BLOOD VESSELS. 



/. Lymphatics. 



1. Inflammation of the lymphatics is termed lymphangitis. 

 It is generally secondary to some inflammation of the tissues 

 and may extend beyond the original affection, as from a wound 

 in the hand to the lymphatics and glands of the axilla. Red 

 and painful streaks may go from the wound to the nearest 

 lymphatic glands. In lymphangitis the contents of the vessels 

 are more abundant and richer in cells. The fluid is often puru- 

 lent or fibrinous, while the endothelium is swollen and disinte- 

 grated. 



2. Occlusion of lymphatics, or lymphangiectasis, is from in- 

 flammatory engorgement, pressure from without, or the pres- 

 ence of parasites or tumor elements. 



3. Lymphatic tumors, or lymphangiomata, and other vas- 

 cular new growths will be described hereafter. It must be 

 remembered that the lymph channels afford the most ready 

 means of propagating new growths, such as carcinoma and 

 epithelioma. 



//. Arteries and veins. 



\. Inflammation in arteries is termed arteritis, and of veins 

 phlebitis. It may be purulent or hyperplastic. In syph- 

 ilitic arteritis the inner and outer coats are usually more thick- 

 ened than the middle one. Tuberculous inflammation of the 



