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T H E JOURNAL OF I N D U S T R I A L A N D ENGINEERING CHEMISTRY COMPARISON OB N I T R O G E N I N T O P S A N D R O O T S
Graph 2 gives the ratio of the nitrogen in the roots t o t h a t in the tops and shows the wide variation in the nitrogen content of the tops in ralation t o t h a t in the roots. I-In the bank sand series the nitrogen in the tops averages a little over twice t h a t in the roots. On 6 out of the g plots there was over twice the per cent of nitrogen in the tops t h a t there was in the roots, The 3 plots on which the nitrogen in the tops is far removad from the average are the check plot, phosphorus plot, and the nitrogen plot. 2-In the sand and manure series the nitrogen in the tops averages approximately 1’/6 times t h a t in the roots. The only fertilizer treatment which is widely divergent from the average is the nitrogen (alone) plot.
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3-111 the brown silt loam series the nitrogen in the tops averages a little over I ~ / S times t h a t in the roots. Only one plot is widely divergent from the rest, namely, the manure-nitrogen-phosphorus plot. 4-Leaving out the plots t h a t are widely divergent, we have the following: 2 . 0 6 times the per cent nitrogen in the tops of plants grown in bank sand as there is in the roots; I . 3 1 times the per cent nitrogen in the tops of plants grown in brown silt loam as there is in the roots; I. 2 4 times the per cent nitrogen in the tops of plants grown in brown silt loam as there is in the roots. SUMMARY
I-The nitrogen content of head lettuce plants grown in different soils varies greatly. 11-Different fertilizers affect the nitrogen content of head lettuce plants on the same soil. 111-The same fertilizer treatment affects the nitrogen content of plants grown on different soils in different ways. IV-Between the brown silt loam, which was in a good state of fertility, and the bank sand, enriched with manure, there was less difference between the ratio of the nitrogen per cent of the roots t o t h a t in the tops. V-In the bank sand and manure series where manure was used a t the rate of 2 bu. of manure to 3 bu. of sand, fertilization varied the ratio of the per cent nitrogen in the roots t o t h a t in the tops from I O O in roots to 105 in tops, t o I O O in roots t o 1 3 2 in tops. VI-The per cent nitrogen in the tops of the head lettuce plant does not tend t o bear a constant relation to t h a t in the roots. VII-With the per cent nitrogen in the roots taken as 100,the closest ratio obtained was IOO parts in roots t o I o j in the tops; the widest ratio was I O O parts in roots t o 236 in the tops.
Vol. IO, No. 8
Acknowledgments are made t o Mr. Lester Yoder and Mr. I r a Baldwin for assistance in the analytical work. AGRICULTURAL EXPERIMENT STATION PURDUE UNIVERSITY LAFAYETTE. INDIANA
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AN ANAEROBIC CULTURE VOLUMETER By ZAE NORTHRUP Received May 18, 1918
During the past year, in studying qualitatively and quantitatively the gas production in fruits and vegetables canned in tin and glass, several types of bacteria were isolated. It was desired not only to determine whether these organisms were gas producers and anaerobes, but also to determine with as much accuracy as possible the composition and comparative amounts of the gases evolved in pure culture for purposes of comparison with the gas in the can from which they were taken. An apparatus was needed t o fulfil these requirements which would furnish sufficient gas for analysis, simulate can conditions as nearly as possible, and enable the gas evolved t o be conducted directly t o the gas burette for analysis as had been done with the gas collected from the blown cans. After several preliminary experiments the apparatus illustrated was constructed and found t o work satisfactorily. One of the ideas in its construction was t h a t such a n apparatus, t o be of general use t o laboratories studying gas-producing organisms (in canned goods especially), should consist of stock laboratory equipment and not require the purchase of special and costly apparatus, or the use of large quantities of media. Another idea in its construction, which is mentioned abovd, was t o imitate can conditions by fostering anaerobiosis, i. e . , the organisms grow in this apparatus under anaerobic conditions and produce gas, which collects undzr pressure as in the can, and t o imitate conditions 4n a glasscovered glass can where pressure is not first evidenced by a bulging top as is usual with the tin can or Mason jar. Dr. Wm. Mansfield Clark brought forth the objection t o this apparatus t h a t i t did not give quantitative results since the gases evolved, being under enormous pressures, were partially dissolved in the liquid. However, this same contention would hold true in the study of gases direct from swells and as these gases must be studied under the conditions under which they are produced it seems as if Dr. Clark’s argument would not hold in this case. METHODS O F USE
As will be noted in the accompanying illustration, the materials necessary for the construction of the anaerobic culture volumeter are a separatory funnel with glass stopcock (Squibb’s pear-shaped funnel with graduations possesses some advantages over other shapes), one-hole rubber stopper t o fit, glass stopcock and tubing, tall wide-mouthed bottle of about 300 cc. capacity fitted with a two-hole rubber stopper, a short piece of rubber tubing, and a small Berkefeld filter.
Aug., 1918
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
The separatory funnel and connecting tubing are first filled with the desired liquid culture medium. Enough medium is also poured into the bottle so that the level of the liquid is slightly over the top of the filter. When the stopcock on the funnel is closed, the medium remains in the separatory funnel, due t o atmospheric pressure. For sterilizing the apparatus and the contained medium, a piece of cotton is placed in the tube at the top of the separatory funnel. The cock in the connecting tube is then closed and that at the top of the funnel opened. After sterilization, the cock in the separatory funnel is closed and t h a t in the connecting tube opened. When the apparatus has cooled sufficiently the cock in the connecting tube is closed and t h a t a t the top opened. The inoculation is now made by pipetting into the stem of the separatory funnel any inoculated liquid medium and if the m e d h m does not then reach the stopcwk, sufficient sterile medium is introduced t o make the funnel culture anaerobic when the cock is closed. After this is accomplished the cotton is replaced, the top cock closed, and the lower cock opened. I n the experiments performed, the organismsgrcwin the medium in the separatory funnel and produced gas which forced the liquid medium down and out through the Berkefeld filter into the bottle; the cotton plugged vent prevents the development of pressure in the bottle. Contrary t o expectations and much to the advantage of the experiment the organANAEROBIC CULTUREVOLUMETER isms did not grow A-Cork D-Separatory funnel through the filter for B-Coupling &-Cotton alC-Bacterial filter E-Glass tubing several thus lowing ample time for analysis of the gas formed. The separatory funnel was connected up directly with the gas burette after removing the cotton, and the upper cock was opened very carefully as t h e gas was under considerable pressure. Samples of gas were
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drawn from time t o time from the apparatus and showed but little variation in composition quantitatively and qualitatively. After the organisms grew through the filter, any gas produced escaped through the vent, so this culture could still be used for obtaining gas for analysis under practically the same conditions as before. On the whole this apparatus has proved very satisfactory for the purpose for which it was designed. I have been aided in the perfection of this apparatus by Mr. G. I. Blades, a senior horticultural student. The suggestion has been made since that the Doremus apparatus for quantitative extraction of gases emplqyed by Baker’ could be used in the study of pure cultures by simply inoculating cans, sealing and incubating them, instead of utilizing the apparatus described above. Perhaps in many instances this idea can be put in practice. I employed the Doremus apparatus used by Baker, in the study of gases direct from naturally formed “swells,” previous t o devising the above apparatus and found it entirely satisfactory in this respect, but for pure cultures it has the following disadvantages : the large hole punctured by the Doremus apparatus renders it exceedingly difficult to reseal without introducing either solder, HC1, or foreign organisms. It was found necessary to cut a little square tin, sterilize it, and solder it over the opening when further cultivation was desired. If the Doremus apparatus was constructed to punch a smaller hole, this tube would become easily and quickly clogged with seeds, skins, pulp, etc., of the food under investigation. Again, because of the use of pure cultures i t would be very undesirable t o force water into the can through the gas extraction apparatus as is suggested by Baker. Water has been found to be an undesirable liquid over which t o collect gas from the cans on account of its absorptive power. Mercury has been employed in all our tests. It is not easy t o regulate the amount of gas taken from the can when tin cans and the Doremus apparatus are used, in fact, immediately as the can is punctured, all the gas escapes into the retaining bottle before it is possible t o contiol it. It is not possible t o tell whether all gas has been extracted and shut i t off, until the contents of the can reach the first glass connection. This rzsults in the contamination of the connections and perhaps of the gas apparatus itself with the organisms under study, and if these are sporeformers this is an especially serious disadvantage. The transparency of the glass is one of the biggest arguments in its favor; another argument before mentioned is that it stimulates the conditions in the allglass can which is one of the most highly advocated for the cold pack method.
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BACTERIOLOGICAL LABORATORIES MICHIGAN STATE AGRICUGTURAL COLLEGE AND EXPERIMENT STATION EASTLANSING,MICHIGAN 1 H. A. Baker, “Apparatus for Quantitative Extrattion of the Gases in Canned Food Containers,” Eighlh International Congress of Afifilied Chemzslry, Section on Hygiene, 18 (1912), 43-44, 3 figs.
