1895.J MICROSCOPICAL JOURNAL. 323 



portunities of testing the eflBciency of the method. Out 

 of about oue huudred cultures sealed by my method, and 

 placed on exhibition at Chicago, only about a half dozen 

 became contaminated, and these few in all probability 

 had the contamination in the cotton plugs before the 

 seal was applied, they having stood for some days in the 

 laboratory unprotected. 



On account of the fact that by this method cultures 

 can be easily preserved for a long time (probably for 

 several years), it is of considerable value to teachers and 

 to persons who wish to exhibit cultures publicly. 



The special features of the method are that the seal is 

 perfectly hermetical and is easily and quickly applied ; 

 it is transparent, and can be removed without destroy- 

 ing the culture tube, qualities which make the method 

 eminently satisfactory for the purposes for which it is 

 intended. 



The method is as follows : Flame the end of the culture 

 tube, and with a pair of flamed scissors trim the cotton 

 plug down even with the mouth of the tube. Flame a 

 thick cover-glass of the same size as the mouth of the 

 tube, and lay it on top of the cotton plug. Soak a piece of 

 sheet gelatine for one-half minute in a solution of biclilo- 

 ride of mercury, 1-1000. Remove the gelatine and knead 

 it between the fore-finger and thumb. The heat of the 

 hand will make it sticky. The gelatine is then placed over 

 the mouth of the tube, stretched a little by passing the 

 nearly-closed left hand over the tube. The cover-glass 

 is for the purpose of preventing bulging out or sinking 

 in of the gelatine cover from changes of atmospheric 

 pressure inside the tube. Now. place a small rubber 

 band round the gelatine-covered end of the tube close 

 up under the flange. After the rubber band has re- 

 mained on for two or three minutes, pass a sharp 

 knife round the tube between the band and the flange. 

 The gelatine and band thus cut away can be removed. 



