128 PHYSIOLOGY CHAP. 



Nor does this complete the enumeration of all the enzymes in 

 blood. According to the most recent researches, it further 

 contains oxidases, catalases, and proteolytic enzymes (chymosin 

 and trypsin); nor are the corresponding anti-enzymes or anti- 

 ferments lacking; according to Delezenne there is also an anti- 

 kinase. 



Quantitative Estimation of Fibrinoyen. The quantitative estimation of the 

 fibrinogen or metaglobulin of salted plasma, which also contains paraglobulin, 

 is based on the different solubilities of these two substances in salt solu- 

 tions. Hammarsten (Pfliiyers Arch, xvii., xviii., xix.) has shown that para- 

 globnlin remains in solution in water containing 16-18 per cent NaCl, while 

 fibrinogen, on the contrary, is completely precipitated, and remains soluble 

 only at a lower concentration. If a sufficient quantity of saturated salt 

 solution is added to a vessel containing salted plasma, a flocculent precipitate 

 of fibrinogen is obtained on stirring the fluid briskly with a glass rod. In 

 order to purify this, it is again dissolved, after filtering, in an 8 per cent 

 solution of NaCl, and reprecipitated with concentrated solution as before. 

 This operation is repeated three or four times, and the last precipitate, which 

 is quite white, and held in a filter previously dried at 115" C., and weighed, 

 is placed in a warm chamber at 115 C. to coagulate. The filter is then 

 replaced on the stand ; the coagulated fibrinogen is washed with warm water, 

 to remove the salts, and then with alcohol and ether. The filter and precipi- 

 tate are then dried again, and weighed repeatedly at long intervals, till a 

 constant weight is obtained. It is now easy from the known quantity of 

 blood employed to calculate the fibrinogen content of 100 or 1000 c.c. 



Estimation of Fibrin Ferment. Carbone's is the only known method of 

 estimating the fibrin ferment contained in blood-serum ; it yields compara- 

 tive, not absolute results. This method is based 011 the fact that leech 

 extract acts in regard to the ferment in a manner analogous to that of anti- 

 toxin towards toxin. Carbone mixed a constant quantity of fibrinogen 

 dissolved in 0-8 per cent NaCl, in a series of test-tubes, with a constant 

 quantity of the serum in which the ferment was to be titrated. He then 

 added to the different test-tubes an increasing quantity of leech extract, and 

 eventually made the volume of liquid equal in all by adding 0'8 per cent 

 NaCl. After twenty-four to forty-eight hours he examined the test-tubes 

 and the clot, which only formed where there was little leech extract. He 

 estimated the quantity of ferment by the quantity of extract necessary to 

 neutralise its coagulating action. 



Estimation of Paraglobulin. Magnesium sulphate is added to saturation 

 to a measured quantity of blood serum. The fluid is vigorously shaken, the 

 precipitate in the form of a white paste, finely granulated, is collected on a 

 filter and washed with saturated solution of MgS0 4 , to remove the albumin. 

 If the precipitate left on the filter is coloured, it is dissolved in a dilute 

 solution of MgSO 4 or NaCl, and reprecipitated as before. This operation is 

 repeated several times, and then completed in. the manner described for the 

 estimation of fibrinogen. 



Estimation of Serum Albumin. The serum saturated with magnesium 

 sulphate, from which the paraglobulin has been removed by filtering, can be 

 used again for the quantitative estimation of serum albumin. This can be 

 precipitated by the addition of a small amount of 0'5- 1 per cent of acetic 

 acid. To purify it, dissolve again in water, and reprecipitate with solution 

 of ammonium sulphate. The further treatment is the same as that described 

 above for fibrinogen. Serin is, however, more frequently calculated by 

 difference, as follows : In one portion of serum the paraglobulin is 

 estimated by the preceding method, and in a second portion, equal to the 



