NATURAL INDIGO 6$ 



adapted to Behar conditions. At any rate, the mixture of 

 types proved highly successful when grown in Assam, and the 

 greater part of the supply of Java seed now sown in Behar 

 is obtained from Assam, though some comes from near Cawn- 

 pore, where it is specially grown for seed. Apart from cultural 

 considerations, the aim of botanical research on the indigo 

 plant at Sirsiah was mainly the selection of a variety specially 

 rich in indican. Parnell devoted much labour to this, but 

 disastrous floods seriously hindered it. Not only must the 

 selected plant grow well and give a high yield per acre, but it 

 must also give a high ratio of leaf to total plant. It has been 

 more or less assumed, that the indican content of the leaf is a 

 factor transmitted by inheritance, and Parnell considered that 

 a considerable amount of evidence had been accumulated to 

 that effect. This, however, requires further examination. 



Effect of Cultural and Soil Conditions on Indican Content 

 of Indigo Leaf. — It appears that the above conditions affect 

 the indigo plant so largely as quite to outweigh any improve- 

 ments in the indican content of the leaf transmitted by in- 

 heritance. 



For example, the same seed, probably a mixture of numerous 

 types of plant, is sown on two similar plots, one untreated and 

 the other manured with sect. It is found that the yield of 

 plant per unit area is double on the treated plot, but in spite 

 of this the yield of indigo blue is the same approximately on 

 both. Thus, merely the luxuriant growth resulting from the 

 manurial treatment has had the effect of diminishing the 

 indican content by 50 per cent. On the other hand, it has 

 been shown that land treated with sannai and superphosphate 

 may give double the yield of plant per acre as compared with 

 untreated land, and at the same time may give the same 

 weight of indigo per hundred maunds of plant. 



Seet is rich in nitrogenous compounds, approximating in 

 this respect to farmyard manure in England. Thus, it appears 

 that forcing the growth by a liberal supply of nitrogenous 

 manures tends to lower the indican content, whereas a supply 

 of other necessary substances under conditions which favour 

 root-nodule formation leads to an increased crop without 

 serious diminution in the indican content. In Assam the 

 indigo plant flourishes in a soil sandy, well aerated, and rich 

 in humus and in necessary salts. Under these conditions 

 nodule activity is great, and the indican content is often as 

 much as to give o-8 to 0-9 per cent, of indigotin in the leaf, 

 whereas in Behar the plant grows poorly by comparison, and 

 is as a rule poorer in indican, though largely grown from 

 Assam seed. 



There was thus a considerable amount of evidence, not 



