ROLE OF INFLAMMATION 1 73 



tlic j)lien()nien()n. The endothelial hyperactivity may he initiated 

 hy the skin-preparatory injection. \\'hen this is followed hy a sec- 

 ond stimulus ^vhich reaches the vessel hy the way of the blood 

 stream (reacting factors) , and \vhen there are sinudtaneous slow- 

 ing of the circtdation and perivasctdar inflanunation, thrombosis 

 results. Further studies on the subject are necessary, ho^vever, 

 because morphological proof of endothelial damage w^as lackmg 

 in the studies of Kielanowski and Selzer, Apitz and Gerber. 



Gerber also pointed otit that the extent of thrombosis is not 

 quantitatively dependent on the degree of inflammation present 

 with skin preparation or on that occurring W'ith the phenomenon. 

 During the first f^venty-four hom^s there may be an increase in the 

 degree of thrombosis, possibly as a result of extension of the con- 

 ctnrent inflammation. The degree of thrombosis varied with the 

 type of reacting factors as ^vell as ^vith the skin-preparatory quali- 

 ties of the factors employed. For example, experiments on the elic- 

 itation of the phenomenon by the use of the antigen-f antibody 

 combination as the reacting factors (Chapter ix) demonstrated a 

 more marked degree of thrombosis than ^vhen filtrates of typhoid 

 bacilli were injected intravenously, even though in both instances 

 the skin preparation was productive of identical degrees of moder- 

 ate inflammatory reaction. 



Inasmuch as the earliest changes seen in the phenomenon of 

 local skin reactivity are extreme vascular dilation and engorge- 

 ment, profuse hemorrhage and thrombosis, the reaction may be 

 sharply differentiated from reactions of protein hypersensiti\'eness 

 even on the morphological basis. The follo^ving recapitulation 

 of morphological appearance of the Arthus phenomenon gi\'en 

 by Opie (1924c/, b) may be in place: 



"The reaction of the Arthus phenomenon makes its appearance 

 within teir days after the injection of a protein but does not reach 

 maximtnn intensity until the animal has received six or eight in- 

 jections at intervals of several days. 



"The Arthus phenomenon resembles \'ery closely the tuber- 

 culin, luetin and typhoidin reactions. 



"T^venty-four hours after the injection of the test protein, the 

 skin and the subcutaneous tissues become edematous and infiltra- 

 ted with polymorphonuclear neutrophile leucocytes. The epithe- 

 lial cells of the lo\\er layers are SAvollen. After forty-eight hours 

 the stratum corneum separates from the stratinn lucidum by exu- 

 date rich in leucocytes. The cells of the Malpighian layer are 



