v.] THE BLOOD. 33 



excess of syrupy solution of NaHO, then dilute CuSO^. Pink 

 colour indicates peptones. 



[6. Gelatin (albuminoid), gives Xanthoproteic and Millon's re- 

 actions, gives a violet colour with ISTaHO and CuSO^, is not coagu- 

 lated by boiling, and is not precipitated by acetic acid and potas- 

 sium ferrocyanide.] 



III. Test for Carbohydrates. First remove derived albumins 

 by neutralising and filtering, and native albumin and globulin by 

 boiling and filtering. 



1. Acidulate if necessary and add iodine. 



(a.) Blue colour, disappearing on heating and returning on cool- 

 ing, indicates starch. 



{b.) MaJiogany-hroion colour, disappearing on heating and return- 

 ing on cooling, indicates glycogen or dextrin. Add basic lead 

 acetate, precipitate (if proteids are absent) = glycogen. 



2. Test for reducing sugar by Trommer's test. If present, dis- 

 tinguish glucose, maltose, and lactose, by the phenyl-hydrazine test 

 (p. 2l). 



3. If no starch, dextrin, glycogen or reducing sugar, examine for 

 cane-sugar by inversion test. 



LESSON V. 

 THE BLOOD— COAGULATION- ITS PROTEIDS. 



1. Reaction. — Constrict the base of one finger by means of a 

 handkerchief. When the finger is congested, with a clean sewing 

 needle prick the skin at the root of the nail. Touch the blood 

 with a strip of dry, smooth, neutral litmus paper, highly glazed to 

 prevent the red corpuscles from penetrating into the test paper. 

 Allow the blood to remain on it for a short time ; then wash it off 

 with a stream of distilled water, when a blue spot upon a red or 

 violet ground will be seen, indicating its all-aline reaction, due 

 chiefly to sodium phosphate (Na^HPO^) and sodium carbonate. 



2. Blood is Opaque. 



{a.) Place a thin layer of defibrinated blood on a glass slide ; try 

 to read printed matter through it. This cannot be done. 



3. To make Blood Transparent or Laky. — Place 10 cc. of de- 

 fibrinated blood in each of three test-tubes, labelled A, B, and C. 

 A is for comparison. 



(a.) To B add 5 volumes of water, and warm slightly, noting 

 the change of colour by reflected and transmitted light. By re- 



o 



