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*4 MONTHLY. 1> 
Vol. XIV.] 
COLOMBO, MARCH ist, 1895. 
[No. 9. 
NITROGEN 
FIXATION IN ALG.E. 
N Natube of March 29, 189-1, 
vjs/ "iJrxr -7- .A^x 
yr»gV(V /f.&tfAV Prof. Marshall Ward gave a 
/R^- v** £&s^-<W clear and excellent resume of 
^4jK^t c. rtain aspects i f tl e question 
of nitrogen fixation in plants. 
Since the publication of that 
article, fresh and most im- 
port mt additions h .ve been 
made to the subject. 
Last May. P. Kossowitsch published an account of 
species alone, but of several intermingled. Accord' 
ingly when, in 1891, Kossowitsch set himself the 
task of determining whether Algae in themselves 
possess the power of assimilating free atmospheric 
nitrogen or not, the first obstacle he had to over* 
oome was the difficulty of finding a method by which 
he could obtain a single algal species in absolute 
purity. This was ultimately effected by growing the 
Algae on gelatinous silicic acid permeated with a 
nutritive solution, and subsequently on sterilised sand 
also containing food solution. The steps by which 
the isolation was effected were slow and beset with 
his experiments on A'ga) in respect to the r nitrogen I difficulties, which spinas up in the most unexpected 
fixing powers (Hot. Zeitumj, May !6. 1894), and a 
short ucuouir. of this contribution should form an 
appropriate supplement to Prof. Ward's piper. 
In 188% Prof. Frank of Berlin, had s'a'.ed his 
opinion that Algae possessed the power of free nitro- 
gen fixation. 
In 1892, Messrs. S iftloeslh'g and Laurent pnblished 
an account of their classical researches dealing with 
many pants, anion.; which A'gse also fouu I a place. 
Their experimsn's with thess f rim range in two 
series. In the first they found that if they kept 
soil, covered with Alga) an J containing bacteria of 
certain kind*, under observation for some time, an 
incroi'e in nitrogen w.s perceptible. On the other 
hand, if they preventel the format'on of A'goe, 
although the same bacteria remained, there was no 
noticeable addition to the nitrogen of tbe system. 
In the second set of exparimants, in which different 
Algae wero employed, no nitiogon fixation could be 
perceived. It wis evident from this that either 
particular kind i of Algae only h ivo " fixing " powers 
oc that suitable baclecia ware not simu'taneously 
present iu the second cise, and th it AlgiB can only 
fix with the additional aid of these micro organisms. 
In the followiu? yevr. K >eh and Kossowitsch dei-o- 
tod their attention to the subject, and went over 
much the same ground as Laurent and Schloesing 
continuing their results, and adding new facts, the 
value of which, however, was somewhat enhanced 
by the al^al culture? never cousistitig of any single 
nauner, and the pige3 oE Kossowitsch's memoir which 
deal with thi3 subjeci possess a separate and great 
interest of their ow i; spice, however, will not permit 
that the matter bedetailel here. Having obtained the 
Algae iu a state of purity, the next step was to transfer 
them to the appxratus in which their nitrogen-fixing 
powers were to be tested, 
This consisted of a central air-tight vessel con- 
iiected with a sarias of D-ttibes, which were blown 
iato bulbs at cartaia intervals. These bu!b3 contained 
strong sulphuric acid. The whole apparatus wa a 
stariliseil, and the Algae under consideration sown 
upon a sterilised nutritive s lbst ratum in the central 
vessel. Air freed from alt tra333 of nitrogen com- 
pounds was blown into the %'essel through the 
U-tubes, the sulphuric acd in which killed any 
organisms which might be contained in this air. 
The Alga which was first experimented ou waa 
Cystococcus (or an extremely similar form). Every 
prooaution was takau iu introducing this into the 
apparatus. 
Using a nutritivo solution perfectly free from all 
nitrates, it was see l that the Algae refused to show 
any signs of growth; it ymjrj clear, tharoforo, that 
at least to start devjbpmjiit a trvco of nitr.ue must 
be added to the sand. Tho addition of other nitro- 
gen compounds was found to be useless, and accord- 
ingly a small and accurately-measured quantity of 
a nitrate was mixed with the food solution in the 
central vessel. Tho whole apparatus thus fixed up 
was placed iu the light, and kit for some weeks. 
