TWENTY-THIBD ANNUAL MEETING. 123 



fluid, though before filtering, it may have been fairly milky. But very few bacilli 

 are required, however, to give rise to a typhoid epidemic in the face of favorable 

 conditions. The restraining of the bacilli should be absolute. The following ex- 

 periments were carried on with a view to determining the perfectness of the filtra- 

 tion in the case of the filter under examination : 



Oct. 29, 1890. — Hay cut into short pieces was digested in .8 litre distilled water at 

 55° C. from 4 p. m. to 6 p. m. in water bath. Pieces of hard white were turnip simi- 

 larly digested. 



Oct. 30. — Renewed the digesting for one hour. At 11:30 a. m., filtered the infu- 

 sion through clean filters into clean beakers. The hay infusion was of a rich brown 

 color ; the turnip, colorless. Part of each infusion was put into a beaker, and set 

 aside under a larger inverted beaker. That beaker containing the filtered unster- 

 ilized turnip infusion was labeled 29, the hay 28. (See further reference.) The re- 

 maining portions of the infusions were boiled intermittently (at intervals of about 

 ten minutes) for one hour. Nine test-tubes, (new) thoroughly washed and oven- 

 dried, were taken from the hot oven, flamed, {i. e., the flame from a Bunsen burner 

 was allowed to play on every portion of inner and outer surface, the tube being held 

 in cleaned and flamed forceps,) and suspended in a water-bath. Into these tubes 

 boiling hay infusion was poured. The temperature of the water-bath was brought 

 up to the boiling point and the infusion tubes were allowed to boil intermittently 

 for some time. The mouth of each was plugged with clean absorbent cotton, pre- 

 viously heated in oven and handled with sterilized forceps. Over each plugged 

 mouth a double fold of cotton was closely fastened with a rubber band. The tubes 

 were labelled 3, 4, 5, 6, 7, 8, 9, 10, (one of the nine dropped and was broken,) and set 

 vertically in a rack. Eight tubes of sterilized turnip infusion were similarly pre- 

 pared, and labeled 11, 12, 13, 14, 15, 16, 17, 18 



A number of Sternberg flasks, i. e., small, long-stemmed flasks, made by blowing 

 out glass tubing and drawing the stem out, had been prepared ( hermetically sealed 

 when made) and were charged with the sterilized infusions. The introduction of 

 the fluid was effected by breaking off the tips of the flasks with sterilized forceps, 

 slightly heating the bulbs and pushing their broken stems into the boiling infusion, 

 when the contraction of the cooling air in the bulb would allow the ingress, by the 

 outside pressure, of a small quantity of the liquid. The tip of the stem was then 

 sealed by holding in a Bunsen flame. Six flasks were charged with sterilized hay 

 infusion and placed together in a beaker labeled 19 ; six were similarly charged 

 with turnip infusion and placed in beaker 20. After the introduction of the boil- 

 ing liquid it was in some cases boiled in the flask, but not always. 



Two sterilized test-tubes were charged with sterilized hay infusion and placed in 

 rack with mouths open. These were numbered 22 and 23. A third tube containing 

 sterilized hay infusion was loosely plugged with cotton, and labeled 24. Two open 

 tubes of turnip infusion were prepared, and numbered 25 and 26. The remainder 

 of the hay infusion, sterilized, but allowed to stand for three hours uncovered, was 

 poured into an open test-tube and labeled 27. With the open hay tubes a defective 

 hay flask, i. e., one which had a small hole in tip of stem, was placed, and num- 

 bered 30. 



November 3d the earthenware filter was taken from the metal cistern and heated 

 in oven at high temperature for one-half day. It was then thoroughly flamed and 

 its small mouth plugged with clean cotton, and cotton tied over it. It was then sus- 

 pended, after cooling so that no undue expansion might make it less perfect in its 

 filtration, with the plugged mouth projecting, in a nutrient solution known as 

 Pasteur's solution (calcium nitrate, 4 parts; potassium phosphate, 1 part; magne- 

 sium sulphate, 1 part; potassium nitrate, 1 part; distilled water, 700 parts), which 



