108 SCIENCE PROGRESS 



decomposed by putrefying bacteria into indole and scatole, 

 amongst other substances. Indole is a frequent end-product 

 of bacterial growth in protein material, but it is also found in 

 phanerogamic plants. It occurs, for instance, to the extent of 

 2'5 per cent, in the essential oil of jasmine. This oil also 

 contains anthranilic acid, a substance which is obtainable from 

 indigo, another derivative of indole. This fact suggests that 

 all these substances originate from the indole nucleus of protein. 

 In the animal organism indole is excreted in the urine as an 

 ethereal sulphate (indoxyl-sulphuric acid), whereas in plants it 

 is nearly always combined in the form of a glucoside, called 

 indican. By the action of an enzyme (indoxylase, Beijerinck), 

 which occurs in the leaves of indigoferous plants, the glucoside 

 is split into dextrose and indoxyl, and the latter is oxidised, 

 possibly by the help of a peroxydase, into indigo. 



Scatole is another member of the same family, being /3-methyl 

 indole. In animals it is one of the final cleavage products of 

 protein, and is excreted mainly in the fasces ; but it also occurs 

 in plants, and has been found by Dunstan to the extent of i per 

 cent, in the wood of a Javanese tree (Celtis reticidosa, Miq.). 



In connection with the end-products of protein katabolism 

 another group of glucosides ought to be mentioned, which are 

 characterised by the ease with which they split off prussic 

 acid, when acted upon by such enzymes as emulsin. Until 

 recently amygdalin, whose carbohydrate radicle still awaits 

 identification, was the only representative of this group. The 

 researches of Dunstan and Henry have made known quite a 

 series of other well-characterised glucosides, of which Dhurrin 

 from Sorghum plants contains oxymandelic acid, whilst 

 Phaseolnnatin (from Phaseolus lunatus) gives rise to acetone, 

 in addition to dextrose and prussic acid. 



Glucosides containing both nitrogen and sulphur are found 

 widely distributed in plants. It is one of the interesting pro- 

 blems of bio-chemistry to trace their relationship to the cystine 

 radicle of the protein molecule. These glucosides occur mainly 

 in the seeds and vegetative organs of the Cruciferae, which 

 usually also contain, in separate cells, a hydrolytic enzyme, 

 called " myrosin," and Gadamer has lately studied very com- 

 pletely the two best-known glucosides of this type found in 

 mustard seeds. Sinigrin, from black mustard seeds, is split by 

 myrosin into mustard oil (allylsulphocyanide), dextrose, and 



