ARROWROOT 129 



part of South America and is now extensively cultivated in nearly 

 all tropical countries. One-year old rhizomes are collected, carefully 

 washed, then beaten into a pulp, mixed with water and the starch 

 removed by filtering through copper sieves; this is then carefully 

 dried and shipped to market in kegs. The commercial supplies come 

 chiefly from St. Vincent and Bermuda. The rhizome yields about 

 20 per cent of dried starch. 



Bermuda Arrowroot occurs in the form of somewhat hard, irreg- 

 ular granules or masses, varying from 1 to 6 mm. in diameter. When 

 rubbed between the fingers it is reduced to a smooth powder, which is 

 velvety to the touch. The starch grains (Fig. 20) vary in shape 

 from ellipsoidal to ovoid or oblong and from 0.010 to 0.065 mm. in 

 diameter. The lamellae are mostly indistinct and there is usually a 

 transverse or crescent-shaped cleft at the middle or near the broad 

 end of the grain. 



St. Vincent arrowroot is slightly darker in color and is in the form 

 of masses or granules, which are sometimes 20 mm. in diameter. 

 The starch grains resemble those of the Bermuda arrowroot, but the 

 grains having clefts are more numerous. 



The arrowroot starches all show a distinct cross with the micro- 

 polariscope and a marked play of colors when a selenite plate is used. 



Maranta starch contains about 10 per cent of water, and less than 

 1 per cent of ash, the remaining portion consisting chiefly of starch 

 grains except for certain impurities. Owing to the fact that it enters 

 largely into infant and convalescent foods it should be as free as pos- 

 sible from these impurities. Upon boiling 1 part of starch with 10 

 parts of diluted hydrochloric acid, for ten minutes with occasional 

 shaking of the mixture and filtering, the starch grains should not 

 become agglutinated nor the filtrate mucilaginous or emit an unpleas- 

 ant odor. When examined on the thermo-stage of the microscope 

 the granules begin to swell at 70 C. One part of starch heated to 

 100 C. with 20 parts of distilled water gives a transparent, mucilag- 

 inous mixture which is practically free from odor. 



Maranta starch sometimes becomes moldy and should not be 

 used, although Procter stated that he was able to restore musty 

 arrowroot to its original condition by washing it thoroughly in water 

 and then drying. 



So-called American Arrowroot consists of one of the other com- 

 mercial starches, as potato or corn and may be readily detected by 

 means of the microscope (Fig. 20). 



The name Arrowroot is applied to the starches obtained from a 

 number of different plants. Tahiti Arrowroot is obtained from Tacca 



