hi] vessels, etc., used in cultivations 41 



As stated above, a plug of sterile cotton-wool tolerably 

 firm, of about one to two inches, is used for the plugging of 

 the flasks and test-tubes. An assertion such as that made 

 by Dr. Williams at the British Association (Bio- 

 logical Section, September r883), that cotton- 

 wool plugs are not reliable, because they do 

 not protect the fluids in the vessels plugged with 

 them from accidental air-contamination, is to 

 be accepted only as applying to very loose 

 plugs and to cotton-wool not properly sterilised. 

 To good firm plugs of sterile cotton-wool it 

 evidently cannot apply, since all the results of 

 all workers in this field (Pasteur, Sanderson, 

 Cohn, Koch, Klebs, Buchner, and many others) 

 are against it. 



Instruments, such as the points of needles, 

 and forceps, used in the processes of cultiva- 

 tion, lifting up cotton-wool plugs, making cotton- 

 wool plugs, inoculations, &c., must be heated 

 in the open flame of a Bunsen burner, if they 

 are to be absolutely relied on for cleanliness. 

 Scissors and knives used for cutting tissues 

 which are intended for inoculation, ought to be 

 likewise scrupulously clean. One ought to keep 

 a special set of instruments in a metal box, the 

 whole capable of being sterilised in the hot 

 air-chamber. 



Syringes used for cutaneous, subcutaneous, 

 or other inoculations, ought to be capable of -* 

 being sterilised by heat. The ordinary Pravaz 

 syringe of vulcanite not being capable of undergoing this 

 process, Koch has devised a glass syringe similar to the 

 Pravaz syringe. I do not use any syringe for inoculation 



