248 PROCESS OF GASTRIC DIGESTION. 



finally peptone. The products vary, however, with the proteid digested. Kiihne 

 has shown that the proteid molecule is split up, and yields two groups, which he 

 calls anti-peptone and hemi-peptone ; the former can be split up into leucin and 

 tyrosin by trypsin, while the latter does not undergo this change. A mixture of the 

 two he calls ampho-peptone. The intermediate body or pro-peptone, is really a 

 mixture of several bodies. Kiihne called it hemi-albumose. These intermediate 

 bodies from albumin are called albumoses, from globulins globuloses, from casein 

 caseoses. Halliburton calls all these intermediate bodies "proteoses."] 



Properties. Hemi-albumose, although a composite body, gives the following reactions : It is 

 highly soluble in water ; when heated to 50 to 60 it becomes somewhat turbid, but when boiled 

 it becomes clear, and gets turbid again on cooling. This effect is most marked when it is treated 

 with acetic acid and sodic chloride, or the latter alone. It is precipitated by acetic acid and 

 potassic ferrocyanide, but the precipitate disappears on heating and reappears on cooling. It 

 gives the biuret rosy tint reaction like peptones. . It is precipitated by nitric acid, and the pre- 

 cipitate adheres to the glass, but is soluble in the acid ivith the aid of heat, yielding a yellow 

 fluid, but is precipitated on cooling. It is precipitated by boiling with acetic acid and a strong 

 solution of sodic sulphate, metaphosphoric acid, and pyrogallic acid (Kiihne). It is said to be 

 present in all animal tissues except muscle and nerve ( 293). 



[ATbumoses are the first products of the splitting up of proteids by enzymes, and 

 from them peptones are ultimately formed. They may be made from Witte's 

 peptone, or by the peptic digestion of fibrin. Such a mixture, on being neutralised 

 with sodic carbonate, gives a copious precipitate of para-peptones, which can be 

 filtered off, leaving a clear solution of albumoses. On saturating the clear fluid 

 with NaCl, a dense white precipitate, consisting of three albumoses, called proto-, 

 dys-, and hetero-albumose is obtained ; a fourth, deutero-albumose, remains in 

 solution, but can be precipitated by adding acetic acid. If the albumose precipitate 

 be treated with 10 per cent. NaCl solution, proto- and hetero-albumose are dissolved, 

 leaving dys-albumose undissolved. Dialysis of the saline solution precipitates 

 hetero-albumose, leaving proto-albumose in solution. It is probable, however, that 

 hetero- and dys-albumose are identical, or that the former is merely an insoluble 

 form of the latter. The albumoses are bodies intermediate between albumins and 

 -peptones, and of the three, deutero-albumose is nearest to peptones.] 



[Properties. Proto-albumose is soluble in distilled water, is not changed by heat, but is pre- 

 cipitated by saturation of the solution with sodic chloride, by HN0 3 , acetic acid and potassic 

 ferrocyanide, copper sulphate, mercuric chloride. Deutero-albumose is yery like the foregoing, 

 but it is not precipitated by HN0 3 or on adding sodic chloride to saturation, but precipitation 

 occurs when 20 to 30 per cent, of acetic acid is added. Hetero-albumose resembles a globulin in 

 its properties ; it is insoluble in distilled water, but is soluble in saline solutions (10 to 15 per 

 cent.), and is partly precipitated from its solution by saturation with NaCl or dialysis. It is 

 coagulated by heat. All give the rosy-pink colour with the biuret-reaction, and they are all pre- 

 cipitated by saturation with neutral ammonia sulphate, which peptones are not (Kiihne and 

 Chittenden).'] 



[Globuloses from the globulin of ox-serum are obtained in the same way, although the ferment 

 has much less action on globulin than on albumin. Speaking generally, they resemble the 

 albumoses]. 



By the continued action of the gastric juice, the pro-peptone passes into a true 

 soluble peptone. The unchanged albumin behaves like an anhydride with respect 

 to the peptone. The formation of peptone is due to the taking up of a molecule 

 of water, under the influence of the hydrolytic ferment pepsin, and the action 

 takes place most readily at the temperature of the body. Gelatin is changed into 

 a gelatin-peptone. 



According to Kiihne, the proteid molecule contains two substances preformed : anti-albumin 

 and hemi-albumin. Gastric juice atjfirst converts them into anti-albumose and hemi-albumose, 

 and both ultimately into anti-peptone and hemi-peptone ( 170, II.). Only the latter is split up 

 by trypsin into leucin and tyrosin. 



The greater the amount of pepsin (within certain limits), the more rapidly does 

 the solution take place. The pepsin suffers scarcely any change, and if care be 

 taken to renew the hydrochloric acid, so as to keep it at a uniform amount, the 



