Endothelial Factor in Anaphylaxis 273 



origin in blood vessels and meninges. Nerve cells and appar- 

 ently neuroglia cells do not survive. The wandering amoeboid 

 cells we believe are of endothelial origin. 



The well-known vagaries in duration of incubation periods 

 and intensity of temperature reactions of typhus in guinea pigs 

 render progress slow in these experiments. Our results so far 

 prove that the micro-organism of typhus survives in first "genera- 

 tion" tissue cultures up to fourteen days. 



These experiments with both diseases are being continued and 

 extended, and in the case of typhus with other tissues than those 

 of the central nervous system. 



130 (2090) 



The endothelial factor in anaphylaxis. 



By W. H. MANWARING, R. C. CHILCOTE, and V. M. HOSEPIAN. 



[From the Laboratory of Experimental Pathology, Stanford 

 Vniv ersity, C alifornia . ] 



If the lungs of a normal dog are perfused with Locke's solu- 

 tion, followed by Locke's solution containing 0.25 per cent, to 

 1 per cent, horse serum, no recognizable pulmonary reaction 

 takes place. The rate of perfusion flow remains constant on 

 changing from Locke's solution to the dilute serum. The lungs 

 collapse normally on releasing the tracheal clamp. No frothy 

 fluid escapes from the trachea. 



If the lungs of a sensitized dog are similarly perfused, marked 

 pulmonary reactions occur. These reactions are: 



(a) A 75 per cent, reduction in the rate of perfusion flow. 

 This reduction reaches its maximum by the end of two minutes, 

 with slight tendency to recovery after the third minute. 



(b) An increase in the size and consistency of the lungs, 

 with non-collapse on release of the tracheal clamp. 



(c) The escape of large amounts of fluid from the trachea 

 on releasing this clamp. If the perfusion is now continued, 



