METHODS OF CULTIVATION. 173 



tage of being less fragile, and of standing without 

 support. They are especially useful for receiving 

 a solid culture-medium, such as gelatine solution 

 or jellified blood-serum, as the surface exposed is 

 greater than when test-tubes are employed. The 

 only disadvantage attending the use of bottles is 

 their liability to break when heated in a water- 

 bath ; but this will not happen when Koch's meth- 

 od of sterilization at a low temperature.(140 Fahr.) 

 is employed. The tubes, or wide-mouthed bottles, 

 are next placed in an oven and subjected for an 

 hour or more to as high a temperature as the cot- 

 ton caps will bear without being scorched about 

 300 Fahr. They are then cooled, and the culture- 

 fluid is introduced, without removing the protec- 

 tive cotton-cap, through a little funnel having a 

 long and sharp-pointed neck, which is pushed 

 through the layers of cotton-wadding, either di- 

 rectly or after making a small orifice with a sharp- 

 pointed instrument. Usually but one or two 

 drachms of fluid will be required in each tube. 

 This must be sterilized by heat, after its introduc- 

 tion to the culture- tube, unless it is introduced 

 directly from a germ-proof flask with a slender 

 neck, such as the writer recommends for the pres- 

 ervation of culture-fluids in bulk (Fig. 5, p. 177). 

 In this case, the slender neck of the flask is passed 

 through the flame of an alcohol lamp, to destroy 

 germs which may have settled upon its outer sur- 

 face ; and the hermetically sealed extremity is 

 broken off with forceps which have also been 



