10 TUE TONER LECTURES. 



and others in the spleen and marrow in typhoid. In later 

 convalescence, or shortly after recovery, we find in the marrow 

 many mother-cells holding numerous blood cells, enormous 

 masses of large cells filled with pigment in complete analogy 

 with the observed metamorphoses of extravasated blood. These 

 are especially seen at the sides of the cavernous veins, and must 

 retard still further a circulation already impaired in force b}' a 

 weakened heart. Nutrition is here at its lowest ebb, and as 

 the vessels, from the nature of the tissue in which they run, 

 cannot enlarge in proportion to the needs of the circulation 

 and are themselves more or less involved in fatt}' degeneration, 

 we may readily understand how the lack of nutrition alone, as 

 in Dr. Porter's case previously cited, would cause gangrene of 

 the bone even more readily than in the soft parts in which we 

 know it to be so common. 



That the bones should suflTer from vascular clots, and espe- 

 cially the bones of the lower extremities, where such clots are 

 most frequent, as we shall see, in gangrene, is pi'obable both 

 from analogy and experiment, and from one case in which it 

 has been actually observed in typhoid.' There is no reason to 

 suppose, when thrombosis is so frequent elsewhere, that the 

 bones would escape. Yirchow has shown that in relapsing 

 fever we frequently have infarctus in the marrow. Yolkmann^ 

 gives an excellent case and illustration of necrosis of the tibia 

 and talus from embolism, the result of endocarditis. We need 

 a few similarly exact observations in cases of necrosis from 

 fever, in which death or amputation aflTords the desired oppor- 

 tunity to settle the question positively; but generally the 

 examination, if made at all, is of the most superficial character. 



' See Meusel's Case, p. 15. 



2 Pitha & Billroth's Handbnch, Bd. ii.. Ahth. ii., Lief, i., p. 287. and 

 Latifrenbeck's Archiv. 1864. v. 330. See also Molli^re, Lyon M6d., 1870, 

 pp. 12, 149, 256; 1871, p. 38. 



