518 SCIENCE PROGRESS 



excreted. These results stimulated Nencki to a further investi- 

 gation of the subject, with the object of determining the origin 

 of the indican excreted in the urine. He had noticed the 

 statement in some published work of Corvisart and of Ki'ihne, 

 that an odour resembling naphthylamine (or indol ?) was 

 produced, when gelatine was digested with pancreas. What 

 simpler hypothesis, then, than that indican was produced from 

 indol, which itself was a product of the pancreatic digestion 

 of proteins ? 



These few observations serve, then, as the starting-point of 

 some of the most important of Nencki's works. It was very soon 

 noticed, however, that the peculiar and disagreeable odours were 

 produced only when the digestion took place in the absence of 

 antiseptics, and it was soon recognised that the production of 

 bodies causing these odours was due to the presence of micro- 

 organisms. Nencki and his pupils then proceeded to isolate the 

 various products that are produced when proteins of different 

 origin are allowed to putrefy. The earlier investigations were 

 generally made by allowing pancreas to act on proteins in the 

 absence of antiseptics. During the course of these researches, 

 others, such as Pasteur and Koch, were employed in the elabora- 

 tion of the methods for obtaining pure cultures. Nencki's later 

 works on putrefaction were undertaken, therefore, with pure 

 cultures, and the products of putrefaction under certain specified 

 conditions were accurately studied. His first important dis- 

 covery consisted in the actual isolation of indol from amongst 

 the products of protein degradation. By allowing various 

 proteins to putrefy in the presence of pancreas and then dis- 

 tilling the products, he found, in addition to fatty acids, a body, 

 the properties of which had already been described by Bayer, 

 and which he isolated in the form of the nitroso-derivatives, and 

 also in the free state. Nencki by this means definitely isolated 

 indol as a product of protein degradation, although it was not 

 recognised at first that it was not an ordinary pancreatic 

 digestion product, but due to the intervention of bacteria. 

 These results stimulated Nencki to the investigation of other 

 products obtained under the same conditions. Elaborate 

 researches were made on the gases evolved, the fatty acids 

 produced, and the crystalline degradation products. It was 

 soon recognised that the earliest stage in the protein degradation 

 was a hydrolysis, and Nencki was one of the first to note that 



