Simple Method of Testing the Efficacy of Antiseptics. 389 



used, it exerts any deterrent action on the growth of the 

 micro-organism. 



If, however, it is desired that the effects of a re-agent 

 acting for a short time only should be determined, the method 

 of procedure is as follows : — After allowing the thread to 

 remain for the specified time in the antiseptic fluid, it is 

 transferred to a test-tube in which the sterilised distilled 

 water has been prepared. Here it is well shaken up, and 

 then allowed to remain for five or ten minutes, after which 

 it may be passed through one or two other waters in just 

 the same fashion. It is then transferred to the nutrient 

 medium, and carefully watched from day to day. 



Whichever method be used, control experiments must 

 always be carried out. A thread must be passed through 

 the solution of micro-organisms, and then into a nutrient 

 medium. Other threads should be passed through the 

 B. Termo solution, then through one, two, three, or even more 

 distilled waters, as may be thought necessary, and then into 

 the nutrient media ; and the growths resulting in all these 

 cases should be compared, both as regards rapidity and 

 luxuriance, with any that may appear in the other experi- 

 mental tubes. 



The results obtained in a large number of experiments 

 have proved most satisfactory, and in all it has been demon- 

 strated that the method has the following advantages. The 

 apparatus required is comparatively simple and easily ob- 

 tained or manufactured. The various re-agents, etc., being 

 placed in tubes of the same size, and the glass rod which 

 carries the wire having its own plug attached, the thread can 

 be transferred from medium to medium with great rapidity, 

 and with little danger of coming in contact with other foreign 

 particles, so that the thread is never touched by anything 

 except the materials with which we wish it to come into 

 contact. No extra wires, no forceps, or anything are 

 necessary. The thread may be plunged into a mass of 

 nutrient jelly or fluid, so that the growth may take place 

 along the track of the needle and thread, or it may be allowed 

 to lie on the surface of agar-agar or gelatine, and a surface 

 growth may be so obtained. 



