78 PRACTICAL PHYSIOLOGY. [iX. 



The anti-group is not further split up, but the hemi-group, although not 

 split up by peptic digestion, is split up by tryptic digestion into leucin, 

 tyrosin, and other products. 



The substance hitherto called hemi-albumose has been shown by Kiihne 

 to consist of three albumoses, viz., proto-albumose, hetero-albumose, and 

 deutero-albumose. The first two are precipitated by NaCl, and the last by 

 NaCl and acetic acid. For separation of these bodies which can be obtained 

 most easily from Witte's peptone see 13. 



11. To Prepare Albumose and Gastric Peptones in Quantity. 



(".) Place 10 grams of fresh, well-washed, expressed fibrin in a porcelain 

 capsule, cover it with 300 cc. of 0.2 per cent, hydrochloric acid, and keep the 

 whole at 40 C. in a water-bath until the whole of 

 the fibrin is so swollen up as to become converted 

 into a perfectly clear, jelly-like mass, and it becomes 

 so thick that a glass rod is supported erect in it. 



(b.) Add i or 2 cc. of glycerin pepsin extract or 

 the artificial gastric juice, 1 (c.), and stir the mass. 

 Within a few minutes the whole becomes fluid. 



(c.) After a short time fifteen to twenty minutes 

 before the peptonisation is complete, filter and 

 exactly neutralise the filtrate with ammonia or 

 caustic soda, which precipitates the acid albumin 

 with a small quantity of the albumoses. Filter ; 

 the filtrate contains the albumoses, which can be 

 precipitated by saturation with crystals of neutral 

 ammonium sulphate. To get rid of this salt the 

 precipitate must be dialysed in a Kiihne's dialyser 

 (%. 43)0 



12. Comparative Digestive Power of Pepsins, 

 e.g., the various pepsins found in the market, or 

 the comparative digestive power of glycerine ex- 

 tracts of the stomach. Chop up well-washed and 

 boiled fibrin, and stain it with ammoniacal carmine 

 (24 hours). Wash thoroughly and preserve under 

 ether. Place in the requisite number of beakers 



Fro A Kiihne'a Dialvser ' 2 P er C6nt ' HC1< > e( l llal amounts of the carmine 

 A pSchtnent tube such as fibrin, and then add the pepsin whose strength 

 is used for sausages, is sus- is to be tested ; keep at 40" C. As the fibrin is 

 pended in a vessel through digested the carmine is set free, so that the most 

 WimallyTowing. kept con ' deeply-stained liquid contains the most active 

 pepsin (Griitzner's Method}. 



13. Albumoses. Dissolve Witte's peptone in 10 per cent, sodium chloride 

 solution and filter. This solution does not coagulate on heating, but gives 

 the ordinary proteid reactions, together with biuret and nitric acid tests 

 (Lesson I.). 



(a.) Saturate the solution with (NH 4 ).;S04 = precipitate of albumoses. 

 Filter. The peptone is in the filtrate and can be precipitated by alcohol. 



(b.) Dialyse another portion of the solution; heterd-albumose is precipitated. 



(c.) Faintly acidify another portion of the solution, and then saturate it 

 with sodium chloride = precipitate of proto-albumose and hetero-albumose. 

 Filter. The filtrate contains the deutero-albumose and peptone. Precipitate 

 the deutero-albumose by saturating with ammonium sulphate. 



