356 



Mr. H. S. Fremlin. 



[Feb. 23, 



" On the Culture of the Mtroso-bacterium/ 5 By H. S. Fretilin,. 

 Lymph Laboratories, Chelsea Bridge. Communicated by Sir 

 Michael Foster, K.C.B., See. B.S. Eeceived February 23, — 

 Eead March 12, 1903. 



(Carried on at Westminster Hospital Medical School and the Jenner Institute of. 

 Preventive Medicine.) 



My object in undertaking this work was in the first place to obtain 

 a pure culture of the nitroso-bacterium ; in the second place to discover 

 whether it really was a fact that this species was unable to grow in. 

 the presence of organic matter, as stated by Winogradsky.* 



My experiments with the nitroso-bacterium appear to show that : — 



1. A practically pure culture of the bacterium can be obtained 

 after sub-culturing for 7 months in AVinogradsky's ammonia solution. 



2. That the nitroso-bacterium will grow in this solution in the- 

 presence of organic matter. 



3. That the nitroso-bacterium will grow not only on silica jelly, but 

 also in any ordinary organic medium. 



In the course of these experiments pure cultures were again and 

 again obtained by plate cultivation from a great variety of artificial, 

 media. Single colonies therefrom were sub-cultured, and these were 

 commonly competent to convert ammonia in a solution into nitrous- 

 acid. I infer, therefore, that there are not two separate and distinct 

 species of bacterium, morphologically similar, and able to persist side- 

 by side indefinitely in inorganic solutions apart altogether from other 

 bacteria, the one able to convert ammonia into nitrous acid and 

 cultivable only in special media, the other growing on ordinary media 

 but with no ability to convert ammonia into nitrous acid. 



The purpose of my paper is to show that I have been dealing with: 

 a single species of bacterium, which is not only able to oxidise ammonia 

 but is capable also of growing in ordinary organic media. 



The solution used by Winogradsky for growing the nitroso-bacterium. 

 consists of water containing 1 per 1000 ammonium sulphate, 1 per 1000' 

 potassium phosphate, and 1 per 100 magnesium carbonate. The car- 

 bonate solution is sterilised separately, and added to the solution of 

 salts after sterilising, to prevent chemical decomposition. 



This solution I have continued to use all through the work, and in 

 this paper it will be referred to as the " ammonia solution." It has 



* It was in 1895 that, in view of Winogradsky' s work, I commenced these 

 investigations. Since that date, and while mv own research has been in progress, 

 I have studied, in their bearing on the subject of my labours, a number of papers 

 in various journals by a number of observers, whether in criticism or in support 

 of Winogradsky's thesis, as will be seen on reference to my " full " paper. 



