302 



MICRO-ORGANISMS IN WATER 



were added by Trenkmann exceeds that- generally pre- 

 sent in ordinary drinking waters. 



Again, in the inoculation of the cholera organism 

 considerable quantities of organic material must also 

 have been introduced into the waters, for the bacilli 

 were abstracted direct from broth-cultures by means of 

 a needle-loop, in which manner, of course, an appre- 

 ciable amount of broth was also introduced, and the 

 character of the water materially altered. This error 

 is one, as we have already pointed out, which has been 

 unfortunately made by many investigators, and has 

 greatly detracted from the value of the results obtained. 



The following table may be cited as an example of 



the mode of investigation pursued, and of the results 



obtained :• — 



Table I. — Sterile Well loater 



The Waters were Maintained at 21-24° C. 



On the coutrol- plate, poured immediately after the introduction of the bacilli, there were 



/ 1,440 1 



1 1,880 r 



colonies of cliolera bacilli. 



1 1,880 [ 



* 25-27 drops =1 c.c. 



t It is much to be regretted that this investigator has departed from the time-honouxed cus- 

 tom of determining the number of bacteria in 1 cubic centimetre, and has substituted for this the 

 irrational and ephemeral unit of volume represented by the drop of liquid contained in a par- 

 ticular needle-loop in liis possession. 



