INDIGO 249 



insoluble in water. The exact character of this enzyme, and 

 especially its conditions of formation in the plant, afford 

 material for further study. According to Beyerinck it is not 

 an oxidase, nor has he been able to find this class of enzyme 

 in the indigo plant. 



As a result of all these researches improvement in the 

 present method of native indigo production is to be sought 

 along the following lines of investigation : 



1. New plants such as the Indigofera sumatrana, giving a 

 greater yield of indigo, may be introduced. 



2. The study of seasonal variation in the percentage of 

 indican in the plant may result in an increased yield. 



3. The effects of manuring may be further studied, with 

 special attention, it may be, to the organisms in the soil. The 

 indigo plant is leguminous, and possesses root nodules, which 

 also call for investigation. 



4. The accurate control of the beating or blowing operation. 

 In view of the researches of Brown and Morris, it might 



even be suggested that the time of day at which the plant 

 was gathered would condition, to some extent, the pro- 

 portion of indican present in the leaves ; and the suggestion 

 made by several workers that the leaves rather than the 

 whole plant should be plucked would seem to be worth 

 attention. 



It must always be remembered, when comparing what are 

 generally called natural processes with artificial methods, that 

 prima facie the advantage lies with the natural method, which 

 depends on the inexhaustible energy of the sun's rays ; when 

 this advantage is coupled with cheap labour and scientific 

 control, such a native process should be able to stand con- 

 siderable competition. It is the scientific control which up to 

 recent years has been lacking, and it may be hoped that, for 

 social and economic reasons, these researches will be successful 

 in maintaining an industry which gives healthy and satis- 

 factory employment to a large number of people. 



