20 CHEMICAL PHYSIOLOGY. 



(3.) If no peptones are present, test for sugar. 



(4.) If peptones are present, evaporate to dryness, dissolve the 

 residue in 98 per cent, alcohol, filter. Evaporate the alcohol 

 and redissolve the residue in water, and test for sugar. 



LESSON III. 



THE BLOOD COAGULATION, 

 ITS PROTEIDS. 



1. Reaction. Prick your finger with a needle and place a drop 

 of the freshly shed blood on a strip of dry, smooth, glazed, neutral 

 litmus paper. Allow it to remain for a short time ; then wash 

 it off with a stream of distilled water from a wash-bottle, when 

 a blue spot upon a red or violet ground will be seen, indicating 

 its alkaline reaction. 



2. Blood is Opaque. 



(a). Place a thin layer of defibrinated blood on a micro- 

 scopic slide, and try to read some printed matter through it. 

 This will be found impracticable. 



3. To make Blood Transparent or Laky. Place 10 cc. of the 

 defibrinated blood provided for you in three test-tubes, labelling 

 them A, B, and C. Keep A for comparison. 



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

 noting the change of colour by reflected and transmitted 

 light. When looked at by reflected light, it is much darker 

 in colour, in fact, it looks almost black, but by transmitted 

 light it is transparent. Test this by looking as in 2 (a.) at 

 printed matter. 



(6.) To C add a solution of taurocholate of soda. Test its 

 transparency as above. In 2, the haemoglobin is still within 

 the blood corpuscles. In the others 3 (a.), (b.) it is dis- 

 solved out, and in solution. 



