140 PROPERTIES OF PEPTONES. [BOOK II. 



sulphuric acid, acquires a beautiful violet colour, becomes weakly fluorescent, 

 and exhibits in solutions, of suitable concentration, an absorption spectrum 

 characterized by a band, similar to that of Urobilin, situated between 

 Frauenhofer's lines b and F. 



Taste of the While the native albumins and true albumins are 



peptones. free from any definite taste, peptones, for the most part, 



are characterised by an intensely bitter taste, which is particularly 

 obvious in milk which has been subjected to the action of proteolytic 

 ferments, even for a short time. It is most probable that, as Kiihne 

 suggested, the bitter taste does not belong to the peptones themselves 

 but to bye products accompanying them, a surmise which is almost 

 proved by the fact that peptones may be obtained which are free 

 from the peculiar bitter taste, and that a secret method exists em- 

 ployed on a manufacturing scale (communicated confidentially to the 

 author) whereby the bitter taste of gastric peptones may be readily 

 destroyed without apparently otherwise affecting them in an appre- 

 ciable manner. 



Ampno-pep- It was snewn by the observations of Schmidt- 



tones have no Mulheim 1 and of Fano 2 that when a solution of de 

 action on the Witte's or Griibler's commercial peptones was injected 

 coagulation of j n ^ o ^ ne blood-vessels of dogs, in the proportion of 

 0*3 grams of the commercial peptone per kilo of the 

 body weight of the animal experimented upon, the blood lost its 

 power of coagulating for a period of some hours. 



Pollitzer 3 , working under Kiihne's direction, shewed however that 

 neither pure ampho-peptones, nor antipeptone resulting from digestion 

 with trypsin, possessed any decided power of influencing the coagu- 

 lation of the blood, such action being due to bodies belonging to the 

 albumose class, which were present in large quantities together 

 with ampho-peptone in the commercial peptones of Witte employed 

 by Schmidt-Mulheim and by Fano. 



Cleavage of It has been stated, that ampho-peptone gives with 

 Ampho-pep- Millon's reagent a very brilliant red colour, whilst anti- 

 tone by the peptone, when boiled with the same reagent, furnishes 

 action of tryp- ye n ow precipitate, at most tinged with red. Since 

 sin, as -well as m -K, , . r ~ A ., -,, T r ec 

 by persistent Mill on s reaction for proteids corresponds with Hoff- 



boiiing with m aim's test for ty rosin, and since its production with 

 dilute suiphu- proteids probably depends upon the formation of tyrosin, 

 ric acid. Kiihne and Chittenden surmised that the cleavage 



products of ampho-peptone might be different from those of anti- 

 peptone. In accordance with this surmise, they found that a few 

 hours' digestion, in a small tube, of 1 gramme of ampho-peptone in 

 10 c.c. of water containing 0'25 per cent, of Na 2 C0 3 with a little 



1 Schmidt-Mulheim, ' Zur Kenntniss des Peptons und seiner physiolog. Bedeutung.' 

 Archiv f. Anat. u. Phys. Phys. Abth. 1880, 3356. 



2 Fano, 'Das Verhalten des Peptons und Tryptons gegen Blut und Lymphe.' Archiv 

 f. Anat. u. Phys. Phys. Abth. 1881, 277297. 



3 Pollitzer, S., 'On the Physiological Action of Peptones and Albumoses.' Journ. of 

 Physiology, Vol. vn. p. 283. 



