376 



Dr. A. B. Green. 



[Apr. 11, 



illuminate a screen of zinc sulphide through a sheet of lead over 1 cm. 

 thick. It discharged a gold leaf electroscope, highly charged with 

 + or - electricity, at a distance of over 6 feet. It caused a brown 

 colouration of glass or talc when applied at a distance of 1 mm. for 

 12—24 hours. 



The experiments which have been made are of two kinds. In the 

 first set investigation was made of the germicidal action of radium 

 emanations, and in the second, endeavours were made to ascertain 

 whether micro-organisms exposed to the emanations became thereby 

 themselves radio-active. 



I. — The Germicidal Action of Radium Emanations. 



The following have been subjected to the emanations of radium : — 



(a) Calf vaccine, together with its contained extraneous bacteria, 

 which in these experiments consisted of S. pyogenes aureus, S. pyogenes 

 albus, S. cereus flavus, S. cereus albus. Both freshly collected and stored 

 calf-vaccine pulp were exposed to radium emanations in the following 

 way : — A layer of pulp not exceeding 0'5 mm. in thickness was spread 

 in the centre of the depression of a hollow-ground glass slide, around 

 the circumference of which depression a metal ring had been cemented. 

 The capsule containing the radium bromide was placed upon the 

 metal ring in such a way that the salt was brought within 1 — 2 mm. 

 of the lymph pulp, nothing separating them but the talc of the capsule 

 and the intervening air. The pulp was thus used in the thinnest 

 practicable layer, in order that the emanations might act as uniformly 

 as possible on all the component parts. 



The vitality of the vaccine and of its extraneous bacteria was tested 

 before, and at varying intervals of time after the exposure to radium ; 

 the former by inoculations on calves, the latter by cultivations on 

 nutrient media. For each such test a small portion of vaccine was 

 removed from the preparation and was mixed with enough sterile water 

 to form a semi-fluid emulsion. A loopful of emulsion was used to 

 inoculate a liquefied tube of nutrient agar-agar, and a plate was 

 established in the usual way. The remainder of the emulsion was used 

 for inoculating a calf. 



(b) The following species of micro-organisms have also been 

 separately subjected to the action of radium : — 6 y . pyogenes aureus, 

 S. pyogenes albus, S. cereus flavus, S. cereus albus, Streptococcus pyogenes, 

 B. prodigiosus, B. proteus vulgaris, B. pyocyaneus, B. typhosus, B. coli 

 communis, B. mallei, B. pestis, B. tuberculosis, the bacillus of Malta fever, 

 Spirillum cholerce Asiatics, and sporing cultures of B. mesentericus 

 vulgatus, B. mesentericus ruber, B. subtilis, B. anthracis, B. tetani, 

 Gartner's bacillus, the bacillus of malignant oedema, and the bacillus 

 of Eauschbrand. 



