26 DR. E. KLEIN. 



over the mouth, the capillary tube is pushed down into the 

 nourishing fluid and then quickly withdrawn, and the plug 

 completely replaced. In this manner I have been very 

 successful in inoculating, without contamination with air 

 organisms, nourishing fluids with the special organism desired 

 to be sown. 



But this method is in so far unpleasant as the spray pre- 

 vents one from seeing easily the capillary tube while being 

 pushed down into the test-tube. Although I used this method 

 a good deal, I have nevertheless recently employed a much 

 simpler method, which yields as good if not better results. 

 In the carbolic-acid spray the chances of contamination with 

 air organisms are small, as I have above stated, and when a 

 contamination with them occurs it is probably through the 

 spray catching them and carrying them into the test-tubes ; 

 but it must be obvious that this is really only a remote chance, 

 considering that in my cases I only momentarily lift one side 

 of the plug sufficient to admit the end of a capillary tube. 



The best and most practicable method which I am now in 

 the habit of using, and which is almost absolutely safe 

 against accidental contamination, is this : the cotton-wool plug 

 of the test-tube or flask containing the nourishing material is 

 pulled out for about half its length ; a capillary pipette 

 having been charged with the fluid to be sown is then gradu- 

 ally and carefully pierced through the remaining part of the 

 cotton wool (thereby clearing itself of adhering particles), 

 introducing it between it and the sides of the vessel; it is then 

 pushed down into the nourishing material and a trace of 

 the seed fluid emptied into the former. The capillary pipette 

 is quickly withdrawn, and the cotton-wool plug pushed down 

 into its old position. If the nourishing material is gelatine 

 pork, it is of course easily possible at will to deposit the seed 

 from the capillary tube either on to the free surface or into 

 the depth. If the seed fluid is to be obtained from an arti- 

 ficial cultivation contained in a test-tube or a flask, it is with- 

 drawn with a freshly made capillary pipette in exactly the 

 same manner as the seed material is introduced into the new 



