586 FERTILITY OF SOIL. Chap. XXIX. 



besi and Shire may be found during several months of the 

 year, they will never be found lower than what we have 

 mentioned. 



The fertility of the soil has been amply proved by its 

 productions. Indigo, for instance, has been found growing 

 wild over large tracts of country, and often attains the height 

 of a man. It has probably been introduced from India, but 

 a species was found at Lake Nyassa equally tall, though it 

 differs from that on the Zambesi in having straight instead 

 of curved pods. In order to remove all doubt as to the value 

 of the latter sort, Dr. Kirk extracted some of the colouring 

 matter from the indigo growing wild at Shupanga, and it 

 exhibited the peculiar coppery streak when a scratch was 

 made on it, which is characteristic of the best article of 

 commerce. 



The cotton collected from a great many districts of the 

 country was found to be of very superior quality. Large spaces 

 are so much impregnated with salt that an efflorescence of it 

 appears all over the surface. In these spaces superior cotton flou- 

 rishes with very little care. We saw some men who had been 

 employed to take canoes down to the coast, sitting on the bank, 

 on soil like this, cleaning and spinning their cotton. When we 

 returned twelve months afterwards, the seeds thrown away 

 had germinated, flourished, and yielded cotton wool, which, 

 when sent to Manchester, was pronounced to be twopence per 

 pound better in quality than common New Orleans ; and not 

 only is the cotton produced of good quality, but it is persistent 

 in the soil to an extent quite unknown in America. We 

 have observed cotton-bushes yielding vigorously in parts 

 where they had not only to struggle for existence against 

 grass towering over their heads, but had for at least ten 

 years to bear up against the fires which annually burnt 

 down them and the grass together. 



