TREES THAT COUNT MANIHOT GLAZIOVII 6 1 



move the outer bark (which is usually a thin, 

 peely, separable substance) of the Manihot in 

 tapping, and to expose the under bark for the 

 actual incisions. In its native habitat the wound is 

 always found to heal rapidly and to produce a new bark 

 -exactly uniform in character with the original. But in 

 many cases of these alienated plants a strange freak 

 of nature invariably happened in connexion with this 

 operation. It was found that on healing taking place 

 the new bark was of a totally different character. It 

 was a much darker colour, very thick and coarse and 

 hard, and quite inseparable a second time from the 

 green layer beneath. Here, then, was a botanical 

 puzzle which baffled the most experienced, and would 

 have perplexed a Ceara State seringueiro could he 

 have seen it. Moreover, the tree had now apparently 

 become quite useless as a rubber-producer, since none 

 of the existing tools were of any avail in extracting the 

 latex to an appreciable amount. One experimenter, 

 however, tried repeated " prickings " of hundreds of 

 young trees daily for over 200 days, and was re- 

 warded with an average yield that clearly demon- 

 strated the futility of the older methods, and at the 

 same time pointed the way to a system which would 

 enable the trees, many of which were now six years 

 old and therefore at their prime, to live up to the 

 character they had earned in other parts of the world. 

 Subsequently various instruments were devised for 

 tapping without removal of the bark, but they never 

 came into general use. Discarding the knife alto- 

 gether, many planters were content to remove the 

 outer bark in vertical strips of not more than 2 inches 



