Various other methods have been used to bring about this beneficial change in hemoglobin. Gioelli (1896) used a medium made up of 1.1 per cent. hemoglobin and 21.5 per cent. malt extract. This is reddish brown in color, becomes clear when neutralized with potassium hydrate and remains so on heating. This added to agar is reported as very favorable in growing this bacillus. Ghon and Preyss described a medium made up of meat, peptone, salt and agar prepared in the ordinary way, but not filtered for at least a week, and then only roughly. This medium is favorable for symbiotic growths. He further used beef blood heated in a soda solution and blood heated in water as hemoglobin preparations to be added to agar. Thalhimer found an amorphous hemoglobin medium to be more favorable than when a purer hemoglobin was used. W. F. Robertson found a hemoglobin agar, prepared by allowing sheep’s blood to clot, decanting off most of the serum, freezing and then thawing what remains and adding 1 c.c. of this to an agar tube at about 60° C., to be very favorable for the growth of B. influenzæ. Cantani used a blood treated with pepsin and hydrochloric acid, digested some days in the incubator, filtered and made weakly alkaline. This mixture was heated for a few minutes, refiltered and added to the medium. He speaks of it as extraordinarily good for B. influenzæ. Blood treated with trypsin has been used by Matthews, Averill, Young and Griffiths, Harris, A. Fleming and others. Fleming further found that this alteration in hemoglobin can be brought about in a number of other ways. Blood boiled in agar (suggesting the Voges agar) and the tubes slanted while hot, blood boiled in water, the clotted blood precipitated and the clear fluid added to agar, or more rapidly by adding equal quantities of sulphuric acid to the blood and a similar amount of potassium hydrate he obtained altered blood suitable for media. He reported that by any of these methods he could obtain a medium very stimulating to the growth of B. influenzæ. By the addition of brilliant green (1 in 500,000) he inhibited the growth of staphylococcus, streptococcus and pneumococcus. For storing cultures of B. influenzæ Fleming found a minced meat medium with the addition of blood to be the best. I have found this medium without the blood to be an excellent one for keeping a great variety of cultures. Bernstein and Loewe have reported the use of gentian violet (1 in 5,000) for the same purpose as the brilliant green used by Fleming. Avery’s oleate blood agar medium he reported to be largely selective. It checked the growth of pneumococci and streptococci, but gave luxuriant growths of B. influenzæ. Pritchett and Stillman have used it with excellent results recovering B. influenzæ from a very high percentage of the cases studied.