boiled, and filtered; 1 per cent of Witte's peptone and one-half of 1 per cent of acid potassium phosphate are added. After these ingredients have been completely dissolved, sodium hydrate is added until the reac tion is approximately 1 per cent acid, phenolphthalein being used as an indicator. The solution is now boiled for one hour and filtered. Seven per cent glycerine is added and the reaction, if affected by boiling, is again brought to the previous degree of acidity—that is, 1 per cent acid to phenolphthalein. The completed bouillon is now put in flasks and sterilized in the usual manner. Agar may be prepared from the abovedescribed broth.

A few attempts have been made to cultivate tubercle bacilli directly from the tissues of guinea pigs upon agar containing acid potassium phosphate, but so far without marked success, the agar prepared in this way being apparently much less satisfactory for obtaining the first growth of tubercle bacilli from animals than hardened egg or dog's serum.

In 1894 Proskauer and Beck," starting with Kühne's synthetic medium as a basis, tried various combinations of the inorganic salts, their object being to eliminate those which were of no use and to determine also what elements were absolutely essential for the growth of tubercle bacilli. The simplest medium upon which they were able to obtain a growth of the tubercle bacillus contained commercial ammonium carbonate, primary potassium phosphate, magnesium sulphate, and glycerine, dissolved in water. This medium was not the most favorable one for the growth of the tubercle bacillus, however, but the elements mentioned were found to be essential to its development. It will be seen that they did not find it necessary to add a chloride to the solution.

Inasmuch as all of the text-books on bacteriology recommend the use of the sodium chloride bouillon, glycerinized, for the cultivation of tubercle bacilli, it has seemed desirable to call the attention of workers in bacteriological lines to the medium which has been used in the Biochemic Laboratory for six years and which has proven itself in our hands far superior to that recommended by the text-books. We have been unable to note any change in the virulence of our cultures as a result of their growth upon the phospate bouillon, and tuberculin prepared from such cultures has proven to be perfectly satisfactory.

a Zeitschr. f. Hyg. u. Infektionskr., Leipz., 18 Bd., p. 128. 1894.

TUBERCULOSIS CULTURES ON SODIUM CHLORIDE AND PHOSPHATE AGAR AFTER HAVING GROWN FOR MANY GENERATIONS ON SODIUM CHLORIDE BOUILLON.

TUBERCULOSIS CULTURES ON SODIUM CHLORIDE AND PHOSPHATE AGAR AFTER

HAVING GROWN FOR SEVERAL GENERATIONS ON POTASSIUM PHOSPHATE BOUILLON.

and faintly stained areas, presenting a beaded appearance very similar to the forms described by Wolbach and Ernst for the brain medium. Culture tubes of egg, prepared by flowing sterile paraffin (melting point 43° C.) over the surface so as to form a streak, as in the tubes noted above, were inoculated with some of the normal growth-that is, growth away from the paraffin-from the original bovine and swine cultures from which the long, thread-like forms were first obtained, and another from a freshly isolated bovine culture marked Heifer No. 213, the surface of the egg near the paraffin streak being inoculated in each case. These cultures showed the same piling up of the growth along the margin of the paraffin as in the original tubes, and at twenty weeks the growth in all these tubes had coalesced at the center, completely bridging over the streak of paraffin, which averaged about 5 mm. in width. Inoculations on plain egg without the addition of paraffin were made at the same time for the sake of comparison, and preparations from these and the foregoing cultures were measured with the following results, the cover-slip preparations being made always from the inner edge of the growth covering the paraffin in the case of those tubes to which the paraffin was added:

Tubercle bacilli grown on egg in contact with paraffin and on plain egg.

The measurements were made with an ocular micrometer and represent an average of the longest forms in each preparation measured. It will be noticed in this case that of the cultures to which paraffin had been added, Swine I was the only one that showed marked lengthening, though both of the other cultures showed a tendency to lengthen out, whereas no such tendency was apparent in the case of the cultures grown on plain egg. The growths in contact with the paraffin all showed beading at seventeen weeks.

A culture tube of egg, prepared by flowing sterile paraffin across the surface, was also inoculated from the inner or encroaching edge of the growth bordering the paraffin in the original bovine culture from which the long, filamentous forms were first obtained. This culture, labeled B1, showed the same piling up of the growth along the edge of

a This culture had been cultivated for thirty-seven generations on bouillon prior to its transfer to egg, and the individual organisms at the time of its transference from the bouillon averaged 2.5 in length.