1911.] Radium Radiations upon Normal Blood. 131 



The usual procedure in estimations of opsonin was adopted and an 

 emulsion of Staphylococcus aureus was used in every case. The first 

 estimation, which was made 19 hours after exposure of the blood to the 

 emanation had begun, gave evidence of a reduction of the opsonic content. 

 The leucocytes used had, however, been subject to the radiations, and were 

 degenerated. In consequence of this action the radiated blood was centri- 

 fugalised and the opsonin content of the supernatant fluid was determined 

 with freshly washed leucocytes. 



After 44 horns' exposure the following result was obtained : — 



Control fluid gave 372 micro-organisms in 60 leucocytes. 



Experimental fluid gave 34 „ 60 „ 



The effect, then, of long exposure is apparently a marked reduction in the 

 opsonin. 



According to some experiments by H. Eeiter,* in which emanation was 

 mixed with blood for short periods of time, an increase of the phagocytic 

 power of blood cells was observed, for to quote from this author — " Soweit 

 nach den Versuchen in vitro zu erteilen ist, scheint die Emanation die 

 phagocytare Tatigkeit der Blutzellen anzuregen, in einzellen Fallen bis 

 zu 30°/ o ." 



The experiment was varied, as, during the previous exposure, the serum was 

 the recipient of products of radiated corpuscles, the action of which might 

 possibly injuriously affect phagocytosis. Some citrated blood was eentri- 

 fugalised and about 1 c.c. of the supernatant fluid was exposed to the 

 emanation and examined on two occasions with the following results : — 



Time of 

 exposure. 



19 hours <f ^ on ^ ro ^ nu ^ § ave 495 micro-organisms in 160 leucocytes, 



l Experimental fluid gave 84 „ 160 „ 



49 f Control fluid gave 388 „ 100 



LExperimental fluid gave 57 „ 100 „ 



In order to test whether there were substances formed in the radiated 

 fluid which might be inhibitory to phagocytosis, further observations were 

 ; made with the two plasmas of the last experiment. The procedure is 

 indicated as follows : — 



Experimental plasma + Control plasma + Micro-organisms + Washed leucocytes. — Film I. 

 I III 

 1 volume 1 volume 1 volume 2 volumes. 



.1 I I I 



Saline solution + Control plasma + Micro-organisms + Washed leucocytes. — Film IT. 



* H. Eeiter, ' Zentralblatt fur Eontgenstrahlen, Eadium, etc.,' 1910, p. 243. 



