PATHOLOGICAL HISTOLOGY 159 



by Fraenkel (1915 2 ), Aschoff (1915), Benda (1915), Ceelen 

 (1916), Grzywo-Dabrowski (1918), and others. According to 

 Ceelen the lesions in the brain were seen and described by 

 Popoff in 1875 as circumscribed areas of cellular infiltration 

 quite similar, when viewed under low magnification, to miliary 

 tubercles. The most comprehensive descriptions of the central 

 nervous system lesions are by Spielmeyer in 1919. Otto and 

 Dietrich in 1918, and Doerr and Kirchner in 1919, found in 

 the brains of guinea-pigs infected with typhus lesions similar 

 to those previously found in man and monkeys. 



A number of workers have found lesions in the heart, kid- 

 neys, and muscles of a similar nature to those described in the 

 skin and central nervous system. While there has been dif- 

 ference of opinion in regard to the sequence of changes to be 

 observed, and to the dependence of the perivascular reaction, 

 both in cerebral and mesenchymal tissues, upon vascular 

 lesions, the various authors have agreed in regard to the im- 

 portant lesions to be found histologically in typhus. 



The admirable and complete review by Ceelen in the Ergeb- 

 nisse of Lubarsch and Ostertag, 1919, makes it unnecessary 

 to review the subject as a whole. Important papers will be 

 referred to in connection with our descriptions. 



(a) The skin: Our descriptions are based upon the study of 

 skin from all parts of the body excised from thirty-six post- 

 mortem subjects and from skin excised from the arm or abdo- 

 men, during life, from twenty-eight patients. From the 

 autopsies we have material from the seventh to the twenty- 

 fourth day of the disease. The skin excisions include material 

 from ths first day of the rash (third day) to the fifteenth day 

 of the disease. 



All descriptions are based upon sections stained with 

 Giemsa's stain after Zenker's fixation. Acetic acid was used 

 in the fixative in order to prevent the staining of mitochondria. 



The presence of lesions is constant in all of our material. 

 The combination of vascular lesions and perivascular accumu- 

 lations (knotchen), forming a pathognomic picture, is present 

 on and after the fifth day. 



