212 DESCRIPTION OF PLATES 



FIGURE 10. Louse Box 65, Louse 10. Rickettsia prowazeki. ^ 



1,200 diameters. Stained with cyanochin blue. The few rickettsia 

 shown in this preparation are not stained. They appear as translucent 

 bodies lying upon a colored background. When so demonstrated, the 

 organisms give the impression of being somewhat larger than they seem 

 to be in preparations stained by Giemsa's method. The diversity of 

 form and size is well shown. 



FIGURE 11. Louse Box 47, Louse 6. Rickettsia prowazeki. 



1,200 diameters. Smear. Contents of louse's mid-gut; granular and 

 bacillary forms are present. 



FIGURE 12. Louse Box 43, Louse 4. Rickettsia prowazeki. 



1,800 diameters. Smear. Contents of louse's mid-gut; bacillary forms, 

 measuring I/A to 2.8/* in length. 



PLATE III 



FIGURE 13. Louse Box 48, Louse 10. Rickettsia prowazeki. 



1,200 diameters. Smear of a louse's mid-gut; granular and paired 

 forms are seen as well as a tangled skein of rickettsia in thread-like 

 chains from a squashed epithelial cell. 



FIGURE 14. Louse Box 60, Louse 9. Rickettsia prowazeki. 



1,800 diameters. Smear preparation from teased cells of the mid-gut. 

 This illustrates the type form of rickettsia as usually described. 



FIGURE 15. Polish Lice, Louse 19, Dr. Weigl. Rickettsia prowazeki. 



The forms illustrated occurred in a smear preparation made with the gut 

 and gut contents of one of a series of lice given by Dr. Weigl. Dr. Weigl 

 stated that these lice had been infected with Rickettsia prowazeki by 

 feeding upon typhus patients. In the group of rickettsia bodies illus- 

 trated the indefinite bluish stained ground substance and the purple 

 polar or central granules are clearly seen. 



FIGURE 16. Louse Box 57, Louse 42. Rickettsia prowazeki. 



1,200 diameters. Section. The epithelial cells of the gut are greatly 

 swollen and vacuolated. They are packed with enormous numbers of 

 granular rickettsia. The organisms occur as fine granules singly or in 

 pairs. Also present are larger, usually paired, rickettsia bodies which 

 take a deeper stain. " Filaments" (see page 139), of varying size and 

 stained a bright red, are seen in several places. 



FIGURE 17. Louse Box 17, Louse W 231. Rickettsia prowazeki. 



1,200 diameters. Section. Epithelial cell of louse's mid-gut filled with 

 bacillary and paired forms. (See protocol, page 53.) 



