y passed urine in sterile flask.

2. Place the flask in the steamer at 100 deg. C. for thirty minutes.

3. Filter through two thicknesses of Swedish filter paper.

4. Tube, and sterilise as for nutrient bouillon. (Leave the reaction
unaltered.)

~Urine Gelatine.~--

1. Collect freshly passed urine in sterile flask.

2. Take the specific gravity, and, if above 1010, dilute with sterile
water until that gravity is reached.

3. Estimate (with control) at the boiling-point, and note the reaction
of the urine.

4. Weigh out gelatine, 10 per cent., and add to the urine in the flask.

5. Heat in the steamer at 100 deg. C. for one hour to dissolve the
gelatine.

6. Estimate the reaction and add sufficient caustic soda solution to
restore the reaction of the medium mass to the equivalent of the
original urine.

7. Cool to 60 deg. C. and clarify with egg as for nutrient gelatine
(_vide_ page 166).

8. Filter through papier Chardin.

9. Tube, and sterilise as for nutrient gelatine.

~Urine Gelatine (Heller).~--

1. Collect freshly passed urine in sterile flask.

2. Filter through animal charcoal to remove part of the colouring
matter.

3. Take the specific gravity, and if above 1010, dilute with sterile
water till this gravity is reached.

4. Add Witte's peptone, 1 per cent.; salt, 0.5 per cent.; gelatine, 10
per cent.

5. Heat in the steamer at 100 deg. C. for one hour, to dissolve the
gelatine, etc.

6. Add normal caustic soda solution in successive small quantities, and
test the reaction from time to time with litmus paper, until the fluid
reacts faintly alkaline.

7. Cool to 60 deg. C. and clarify with egg as for nutrient gelatine
(_vide_ page 166).

8. Filter through papier Chardin.

9. Tube, and sterilise as for nutrient gelatine.

~Urine Agar.~--

1. Collect freshly passed urine in sterile flask.

2. Take the specific gravity and if above 1010, dilute with sterile
water till this gravity is reached.

3. Weigh out 1.5 per cent. or 2 per cent. powdered agar, and add it to
the urine.

4. Heat in the steamer at 100 deg. C. for ninety minutes to dissolve the
agar.

5. Cool to 60 deg. C. and clarify with egg as for nutrient agar (_vide_
page 168).

6. Filter through papier Chardin, using the hot-water funnel.

7. Tube, and sterilise as for nutrient agar.

(Leave the reaction unaltered.)

~Serum Sugar Media (Hiss).~--

In these media the fermentation of carbohydrate substanc