1869.] Dr. Norris on the Aggregation oj Blood-corpuscles. 429 



magnetized as weakly as is consistent with the condition that the apparent 

 shall not greatly differ from the true dip, we shall obtain two more equa- 

 tions of the form 



n"'(A— B) = (0'") -d, 

 rc""(A + B) = (0"")-0; 



and these four equations, when suitably combined, will determine the values 

 of the three unknown quantities A, B, 0. 



The magnetic moments involved in these equations may be determined 

 with little trouble, and with sufficient accuracy, by placing the needle as a 

 deflector on a unifilar magnetometer, and observing the angle of deflection 

 produced thereby upon the suspended magnet. 



A series of observations has been commenced by the author with the view 

 of testing whether the true dip can be determined exactly with a single 

 needle by the method above described, the results of which he hopes to 

 communicate to the Royal Society hereafter. 



The Society then adjourned over the Whitsuntide Recess to Thursday, 

 May 27. 



May 27, 1869. 



Lieut.-General SABINE, President, in the Chair. 



The following communications were read : — 



I. " On the Laws and Principles concerned in the Aggregation of 

 Blood-corpuscles both within and without the vessels." By 

 Richard Norris, M.D., Professor of Physiology, Queen's Col- 

 lege, Birmingham. Communicated by Dr. Sharpey. Pteceived 

 April 29, 1869. 



(Abstract.) 



In 1827, or forty-one years ago, the phenomenon which forms the sub- 

 ject of this paper was first observed by Mr. Joseph Jackson Lister and 

 the late Dr. Hodgkin. 



To these observers the microscope revealed the fact that if a minute drop 

 of human blood is placed between two plates of glass, the red corpuscles 

 apply themselves to each other by their concave surfaces in such a manner 

 as to form long cylindrical masses, which resemble piles of coin, and that 

 very frequently these piles are so arranged as to form with each other a 

 complete network of rouleaux with clear intervening spaces occupied by- 

 liquor sanguinis. 



Simple as this observation may appear, its importance in a pathological 

 point of view can scarcely be overrated ; for upon its correct interpretation 

 depends our knowledge of the real nature of one of the most marked cha- 

 racteristics of inflammation, viz. the phenomenon of inflammatory or homo- 

 geneous stasis. 



During the forty years which have elapsed since the discovery of this 



