14 



BULLETIN 53, HAWAII EXPERIMENT STATION 



varying from one-fourth to one-half inch in thickness. The outer 

 bark, which is 3 to 12 inches thick, is made up of coarse roots. 

 These appear as air-feeding roots attached to the growing frond 

 which die and form a part of the outer bark of the trunk. 



An examination of the different species shows that Cibotium 

 chamissoi contains a relatively large starch core and a thin exterior 

 covering, and that even the largest specimens of C. menziesii con- 

 tain a small core and a very thick outer bark (PI. VII, fig. 1). 

 Since the removal of the bark is a time-consuming operation at best, 

 C. chamissoi is to be preferred, of the two varieties, for starch 

 making, because it has a larger core and a thinner bark. It is pref- 

 erable also because it contains no dextrins and other material which 

 clog the shredding machine and prevent a complete sedimentation 

 of the starch, as is the case with C. menziesii. The other species, due 

 to their small size, contain cores too small to be of importance for 

 ^starch production. 



The first operation in securing the starch core is that of stripping 

 off the outer fibrous bark as well as the inner shell. The bark is 

 slabbed with a broad-bladed ax while the tree is standing, the work- 

 man beginning as near the top as he can reach and working down. 

 As much as possible of the bark is removed while the tree stands. 

 After the tree has been felled, the remainder of the bark is slabbed 

 off. The core appears as a yellowish-white log, averaging 4 to 8 

 inches in diameter. 3 to 10 feet in length, and 30 to 100 pounds in 

 weight (PL VII, fig. 2). The logs are then carried to the nearest 

 road by donkeys and thence to the mill by truck. They should be 

 milled within 36 hours after cutting to avoid hydrolysis and fer- 

 mentation. Deterioration will not be so rapid if the inner bark is 

 left on the log, but the already heavy cost of hauling will be in- 

 creased by the added weight. 



Experiments in preserving the starch log under water were not 

 successful, due apparently to the partial hydrolysis of the starch into 

 dextrins, with a resultant stickiness that interfered materially with 

 the process of extraction. 



A skilled workman, felling trees averaging 50 pounds to the starch 

 core, should be able to cut about 1,000 pounds a day. Only 4 or 5 

 tons of starch core can be cut from an acre of C. chamissoi, since the 

 mature trees alone are used for starch production: 



Upon its arrival at the mill the starch core is cleansed of adhering 

 soil and bark chips. It is then reduced to pulp by means of a power 

 shredder. The shredder used in this investigation consists of a 

 cylinder of sheet iron which has been fitted on a wooden core and 

 given a roughened surface by having the perforations punched 

 through from the inside. Water is used copiously during 

 the shredding process to prevent the cylinder from becoming coated. 

 The pulp is then run into a revolving screen, where it is sprayed with 

 fresh water. The screen has a tendency to agitate and contains on 

 its inner surface wooden cleats which facilitate washing the pulp 

 free from starch. The milky starch water is run into wooden tanks 

 of about 500-gallons capacity, and the starch is purified by sedi- 

 mentation. The wet, purified starch is then put into sugar centri- 

 fuges, which remove a considerable part of the water at much less 

 cost than would be involved in drying the starch by heat. A 



