DESCRIPTION OF PLATES 219 



FIGURE 58. A loose textured proliferative lesion in the molecular layer of 

 the cerebellum. Autopsy 2, death on the fifteenth day. This lesion 

 represents the nearest approach to the strauchartiges lesion described 

 by Spielmeyer that we have encountered. 240 diameters. 



PLATE XXV 



FIGURE 59. A small mural thrombus covered with endothelium on the 

 endocardium. From a case with thrombosis of the internal carotid 

 artery. Autopsy 18, death on twelfth day. 240 diameters. 



FIGURE 60. A compact proliferative lesion in the cerebral cortex. Autopsy 

 21, death on fifteenth day. This is an illustration of a typical typhus 

 lesion and demonstrates the proliferative character of the lesion and 

 absence of necrosis. At the periphery are numerous elongated neuroglia 

 cells with processes. 400 diameters. 



PLATE XXVI 



FIGURES 61, 62, and 63. Capillaries and precapillaries from two early cases 

 of Mexican typhus showing rickettsia in the swollen endothelium. (See 

 Wolbach and Todd, 1920, 1.) Compare Figure 62 with photomicro- 

 graph in Plate XXXIII, figure 84. 



FIGURE 64. Louse Box 53, Louse 2. Rickettsia prowazeki and Rickettsia 

 pediculi. 



Section. The greatly swollen and vacuolated epithelial cells of the mid- 

 gut are filled with enormous numbers of Rickettsia prowazeki', these 

 usually occur as palely staining granules, either singly or in pairs. 

 Among them are larger granules which stain more deeply and are seen 

 more clearly. The lumen of the gut is heavily infected with larger, 

 more deeply staining rickettsia. These, like the organisms which 

 thickly cover the cuticular border of the gut cells, are Rickettsia pedic- 

 uli. They occur as granules either singly or in pairs. 1,800 diameters. 



PLATE XXVII 



FIGURE 65. A venule of the skin showing a compact cluster of small paired 

 rickettsia. The vessel shows an early lesion, the endothelium is swollen 

 and has taken up red corpuscles. The intima is invaded by leucocytes. 

 There is also a perivascular accumulation of endothelial leucocytes. 

 Compare with the photomicrograph in Plate XXX, figure 75. 

 1,800 diameters. 



