ISOLATION AND CULTIVATION 105 



the tube or flask ; after inoculation cool rapidly by standing 

 the apparatus in cold water until the medium is set. In this 

 way a large number of isolated colonies usually develop, 

 which are either distributed all through the medium, or ap- 

 pear only in the higher zone, or inhabit exclusively the lower 

 layers. The sharply marked distribution of the colonies over 

 the different zones, their size and other characteristics permit 

 a fairly accurate estimate of their relative want of oxygen. 

 The inoculation is made with a long, firm platinum wire, 

 which has previously been brought into contact with the 

 culture material, or a long capillary pipette may be used, 

 into which the culture has been introduced by suction. This 

 simple method, which is very effective even in the case of 

 the strictest anaerobes, is being used successfully in many 

 laboratories. 



Often a layer of sterile medium is poured on top of the 

 inoculated layer after the latter has solidified. In order to 

 gain access to the colonies the tube is broken. Sanfelice 

 recommends warming the bottom of the tube and shaking 

 the column of agar out into a sterile glass dish, where it can 

 be cut into slices, the colonies examined and subcultures 

 made. 



Smith found the fermentation tube to be an apparatus 

 of considerable antiquity and of unknown origin. He says : 

 ^'In Detmer's Pfianzenphysiogischem Practicum I find it 

 figured as Kiihnesches Gahrungsgefass. More recently it 

 has been adapted by Eichorn for the quantitative determina- 

 tion of sugar in urine and by Doremus for that of urea in the 

 same fluid." Smith, 1 in 1889, first conceived the value and 

 made practical application of this tube with reference to 

 anaerobioses and gas-formation among bacteria. With re- 

 gard to its construction Smith says: "In the construction of 

 this simple bit of apparatus several points must be borne in 

 mind. The bulb should be large enough to receive all the 

 fluid contained in the closed branch. Moistening the plug 



1 Smith. Centralb. f. Bakt., Bd. VII (1890) p. 502. 



