'HAP. III.] OTHER PRODUCTS OF DIGESTION BY TRYPSIX. 229 



Employment Trichloracetic acid, CC1 3 COOH, has of late been 

 ic ^ctd as C< a eniployed as a precipitant of albuminous bodies gene- 

 precipitant of ra Uy> k tn i n qualitative and quantitative analyses 1 , 

 aibumoses and Thus it has been used in the quantitative analysis of 

 >tones. albumin in urine and of casein in milk. 



It would appear that this acid throws down both aibumoses 

 tiui peptones, the latter less perfectly than the former. In dilute 

 hit ions of peptones, trichloracetic acid fails to produce a pre- 

 ipitate. 



JECT. 9. ENUMERATION OF THE PRODUCTS (OTHER THAN ALBUMOSES 

 AND PEPTONES) OF THE ACTION OF TRYPSIN UPON THE ALBUMI- 

 NOUS BODIES. 



General Observations. 



Besides the bodies which have been already described as albu- 

 joses and peptones, trypsin when it acts upon the albuminous 

 ies, even in the absence of putrefactive bacteria, gives rise to 

 the appearance of numerous substances, the products of a far- 

 jaching decomposition of the complex albuminous molecule, and 

 r hich are formed altogether independently of oxidation : products 

 are likewise obtained, some in one case, some in another, 

 rhen the same bodies are acted upon by various reagents which 

 ire capable of effecting their hydrolytic decomposition. Thus under 

 the action of solutions of barium hydrate at high temperatures, by 

 fusion with caustic alkalies, by boiling with dilute sulphuric acid, 

 ')y boiling with stannous chloride and hydrochloric acid &c., we 

 obtain from the albuminous bodies proper and from the substances 

 closely related to them (which we have designated albuminoid) 

 several definite crystalline products, which vary somewhat with the 

 nature of the decomposing agent, but of which the chief are 

 represented in the products of a normal ' tryptic ' digestion carried 

 on in vitro, under conditions which exclude the modifying action of 

 putrefactive organisms. 



Amongst the usual, we may say constant, products of the action 

 of trypsin on the proteids is a body which when present in a 

 digestive solution causes it to assume a red colour on the addition of 

 chlorine water, and a more or less violet colour when bromine water 

 is added to it. This product will be discussed in the sequel under 

 the name of ' tryptophan ' (suggested by Neumeister) : a name 

 indicating that it is a colouring matter produced when the proteid 

 molecule is broken down. 



translation of the German original, ' Ueber die Peptone.' Zeitschrift fur Biologic, 

 Vol. xxn. (1886), see p. 450. 



1 Oberniayer, 'Ueber die Anwendung der Trichloressigsaure in der physiologisch- 

 chemischen Analyse.' See a long epitome by Professor Andreasch in Maly's 

 Jahresbericht, Vol. xix. (for 1888), p. 7 10. 



