II. GLASS APPARATUS IN COMMON USE. 



The equipment of the bacteriological laboratory, so 

 far as the glass apparatus is concerned, differs but 

 little from that of a chemical laboratory, and the clean- 

 liness of the apparatus is equally important. The 

 glassware comprised in the following list, in addition 

 to being clean, must be stored in a sterile or germ-free 

 condition. 



Test=tubes. It is convenient to keep several sizes 

 of test-tubes in stock, to meet special requirements, 

 viz.: 



1. 18X1.5 cm., to contain media for ordinary tube 

 cultivations. 



2. 18X1.3 cm., to contain media used for pouring 

 plate cultivations, and also for holding sterile " swabs." 



3. 18X2 cm., to contain wedges of potato, beet- 

 root, or other vegetable media. 



4. 13X1.5 cm., to contain inspissated blood-serum. 

 The tubes should be made from the best German 



potash glass, "blue-lined," stout and heavy, with the 

 edge of the mouth of the tube slightly turned over, 

 but not to such an extent as to form a definite rim. 

 (Cost about $1.50, or 6 shillings per gross.) Such 

 tubes are expensive it is true, but they are sufficiently 

 stout to resist rough handling, do not usually break 

 if accidentally allowed to drop (a point of some moment 

 when dealing with cultures of pathogenic bacteria), 

 can be cleaned, sterilised, and used over and over again, 

 and by their length of life fully justify their initial 

 expense. 



A point be noted is that the manufacturers rarely 

 turn out such tubes as these absolutely uniform in 



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