5. Separate the coagulum from chyle and observe that it has all the properties of fibrine.

6. Treat the serum with ether; it will not become clear. Add acetic acid or caustic potash to the serum, and the ether will then extract all the fat.

7. The addition of acetic acid in sufficient quantity to the serum of chyle causes a precipitate of caseine.

8. Boil the serum acidified with acetic acid and filtered from the caseine, and observe that the albumen is precipitated.

9. In the filtrate prove the presence of peptones by the reactions indicated under Chyme.

10. Evaporate the filtrate to an extract, and precipitate all peptones by absolute alcohol. Evaporate the alcohol from the filtrate. Remove fats by extraction with ether. Then extract by means of ether to which some sulphuric acid has been added. The ether leaves lactic acid on evaporation, to be purified and tested as shown under that paragraph.

11. Examine the extract for glucose by Trommer's alkaline copper-solution.

12. With the fats extracted under 10 some urea is extracted. Separate this by water from the ether residue and test with nitric and oxalic acid.

13. Burn the extract of chyle and analyse the alkaline ash. Observe its great similarity to the ash of the serum of blood; it contains little iron and phosphoric acid, with lime and magnesia, but a considerable amount of chlorine and alkalies, in the latter soda prevails.

Chyme.-1. Subject chyme to dialysis, and use the dialysed liquid, after evaporation to a small bulk, for the following tests, or

2. Obtain peptones from fibrine, albumen, syntonine, or gluten by artificial digestion with pepsine and dilute hydrochloric acid, and use the resulting liquids for these tests.

3. Boil the solution; it is not coagulated.

4. Add pure taurocholic or glykocholic acid; in each case a precipitate is immediately produced.

5. Observe that the solutions turn the ray of polarised light towards the left.

6. Precipitate the solution with absolute alcohol, the white flakes of precipitated peptone are again soluble in very dilute alcohol.

7. Add Trommer's copper solution to chyme or peptone, and observe that it forms a purple fluid. Boil, and if a red precipitate ensues glucose is present in the chyme.

8. Add cupric sulphate, ferric chloride, dilute mineral acids to peptones, and see that no precipitates

ensue.

9. Add chlorine, iodine, tannin, corrosive sublimate, mercuric or mercurous nitrate, silver nitrate, neutral or basic lead acetate, and observe that the peptones give a precipitate with each of these reagents.

10. Boil peptone with mercurous and mercuric nitrite and nitrate with ultimately a slight excess of nitric acid, and observe that a red precipitate and solution results.

11. Ascertain the composition of any peptone pro

duced by process 6, to be almost equal to the original substance from which it was produced by artificial digestion.

Connective tissue.-1. Boil connective tissue with water. It will swell up and at last dissolve. The filtered solution will have the properties of a solution of gelatine (q. v.).

2. Treat with acetic acid; it will swell up and become transparent. Add water and boil. It will dissolve. To the solution add potassium ferrocyanide. No precipitate will ensue.

Corpora lutea. See Ovario-luteine.

Cruentine.-1. Boil the blood-corpuscles, purified as in the preparation of hæmatine, with sulphuric acid. The brown-red flakes of cruentine which form in the liquid must be washed with water till neutral.

2. Dissolve the flakes in sulphuric acid. The spectrum will show three bands.

3. Treat a portion of the dried flakes with ether or chloroform. The red chloroform solution has a spectrum of four bands and a powerful rose-red fluoresence.

4. Treat a portion of the flakes already extracted with chloroform, with alcohol. It will dissolve almost entirely, and the spectrum of the solution will show five bands.

Add ammonia till alkaline, one band will disappear and the others slightly change their position and size. 5. Cruentine dissolved in ammonia shows four bands.

When treated with the ferrous tartrate solution described under hematine, it is reduced and now shows

three bands. Shaking with air re-oxydises it, and restores the former spectrum.

A a BC D

Eb F

G

HH'

Spectrum of reduced cruentine.

6. Treat the chloroform solution obtained in 2 with hydrochloric acid and water. Warm the solution till clear. The spectrum will show three bands. Add excess of ammonia and warm. The three bands are unaltered.

A a BC Ꭰ

E b F

G

HH'

Hydrochloric product of fluorescent cruentine.

7. Boil the flakes obtained in 1 with much alcohol and filter hot. On cooling red flakes will be deposited. Filter, wash with alcohol, and dissolve them in dilute hydrochloric acid, and observe spectrum of two bands.