TRANSACTIONS OF SECTION K. 753 



the Papilionacese, provided the specific organism is first ^rown for two weeks upon 

 a nitrogen-free medium. The present investigation was to test the possibility of 

 cross-inoculation between the organisms found in the root-nodules of the Mimoseaa 

 (Acacia), Alder, and Elcsa(/nus and various Papilionaceie. The acacia uodules were 

 obtained direct from the wattle scrub of Western Australia; the Alder and 

 ElceaipiHs nodules from the Botanic Gardens, Rej^ent's Park. 



The nodules were sterilised first in weak hydrochloric acid, then in formalin. 

 They were cut open under sterile conditions, and a small portion cut out from the 

 centre and placed in 20 c.c. of a culture solution consisting of 1 per cent maltose, 

 0-1 per cent, potassium phosphate, and 0-02 per cent, magnesium sulphate. 

 This was incubated for four days at a temperature of 25° C. Then 1 c.c. of this was 

 used to inoculate a further 20 c.c. of the culture solution, to which had been 

 added 05 per cent, ammonium phosphate. After inoculation for two days the solu- 

 tion became turbid, and was then used for the inoculation experiments. 



Seeds of sweet-peas and tares were planted in pots containing sterilised sand, 

 and watered with a nitrogen-free nutrient solution. After germination one set of 

 pots was inoculated with dilute culture solution, a second set remaining untreated 

 as a control. At the end of four weeks' growth the plants were examined, when 

 it was found that every plant in the inoculated set possessed nodules, whilst not 

 n single nodule was found on the uninoculated plants. 



7. Nitrifying Bacteria in the Velamen oj certain Orchids. 

 By Professor W. B. Bottom ley. 



It has long been known amongst orchid growers that sprinkling urine on the 

 floorof the greenhouse caused a more luxuriant growth of the plants. The am- 

 monia liberated by the decomposition of the urine is absorbed along with the 

 aqueous vapour condensed by the velamen cells, but exactly how the absorbed 

 ammonia was utilised by the plant was not known. 



The result of the present investigation has been to show the presence of both 

 nitrite and nitrate bacteria in the velamen cells. 



The nutrient fiuids used were those recommended by Winogradsky : 1 grm. 

 potassium phosphate, 0-5 grm. magnesium phosphate, 0-5 grm. basic magnesium 

 carbonate in 1,000 grm. distilled water. To this solution is adied 2 grm. ammo- 

 nium sulphate for the nitrite bacteria, and 0-2 grm. potassium nitrite for the 

 nitrate bacteria. 



Test tubes containing 80 c.c. of the culture solution were inoculated with the 

 velamen cells from Cattteya, Dendrobium, Oncidimn, and Angracum, with 

 a control tube in each case. 



The tests used were sulphanilic acid and naphthylamine hydrochloride for 

 nitrites, and phenol-sulphonic acid for nitrates. In every case the tests showed 

 the presence of nitrites and nitrates respectively in the inoculated tubes. 



Growth of the organisms was very slow. After seven days there was only 

 a faint trace of oxidation, but after a month it was very evident. 



8. On the Taxonomic Value of Cilia in Bacteriology. By David Ellis. 



The latest classification of Bacteria— viz., that of Migula — uses the presence or 

 absence of cilia as a diagnostic of ordinal value. The Coccacese are divided as 

 follows : — 



1. Streptococcus . . Dividing in one direction of space, and 



therefore producing chains of cocci. 



2. Micrococcus . . | Dividing in two directions of space, and 



3. Planococcus . . J therefore producing plates of cells. 



4. Sarcina . . . j Dividing in three directions of space, and 



5. Planosarcina . . J therefore producing packages of cells. 



1, 2, and 4 are further distinguished by a want of motility ; 3 and 5 by its 

 1906. 3 c 



