24 CHEMICAL PHYSIOLOGY. 



(d.) Repeat (c.), but place the test-tube in a water-bath 

 at 60 C., the fibrin is dissolved forming acid-albumin. 

 Test for the latter (Lesson I., 7, III., 2). 



(e.) Place a few fibrils in a watch-glass, and pour over them 

 some hydric peroxide; bubbles of oxygen are given off. 

 Immerse a flake in freshly-prepared tincture of guaiacum 

 (5 per cent, solution of the pure resin in alcohol), and then in 

 hydric peroxide, when a blue colour is developed. If the 

 fibrin contain much water, it is preferable to place it first of 

 all for a short time in rectified spirit to remove the water. 

 [Other substances give a blue colour under similar con- 

 ditions.] 



(/.) Suspend some fibrils of fibrin in water in a test-tube, 

 and observe that they give (1) the Xanthoproteic reaction, 

 and that with Millon's reagent (Lesson I., 1). 



(g.) Prick a finger with a needle; collect a drop of blood on 

 a microscopic slide, cover, and examine under a microscope 

 ( x 350). After a time observe the formation of threads of 

 fibrin between the rouleaux of coloured blood-corpuscles. 



13. II. Blood-Serum. By means of a pipette remove the 

 serum from the coagulated blood (Lesson III., 8). If a centri- 

 fugal apparatus is available, any suspended blood-corpuscles can 

 easily be separated by it. Observe its straw-yellow colour. 

 Test its reaction ; it is alkaline. 



Study its proteids. Test first for the general reactions common 

 to all proteids. 



(a.) Dilute 1 volume of blood-serum with 50 volumes of 

 water, and use this for testing. 



(b.) Test separate portions by neutralisation and heat ; 

 nitric acid and the subsequent addition of ammonia ; acetic 

 acid and ferrocyanide of potassium ; Millon's reagent, and 

 the biuret reaction (Lesson I., 1). The solution gives all 

 these reactions. 



Study its individual proteids. 



(A.) Preparation of Serum-globulin (Para-globulin or Fibrino- 

 plastin). 



