B1LOXI, MISS., l!lo:>. 17 



estimation. A good sized, tapering root of tin* hitter White Top 

 variety was selected for examination, one sample comprising the por- 

 tion from the tip up to a diameter of 1 inch and the other the remain 

 der or large part of the tuber. The sample represent 'MIL: tin- laiv 

 end of the root contained 0.028 per cent of prussic acid and the small 

 end contained 0.039 per cent. This point was further confirmed 1>\ 

 the examination of a small root, less than 1 inch in diameter, of the 

 Florida Sweet variety, which contained 0.005 per cent, while the 

 average plant of that kind contains only 0.002 per cent. It is seen 

 that uniformity in hydrocyanic acid content does not exist even in the 

 same variety, it being proportionate to the size of the root. The 

 same conditions obtain in different roots of the same plant. 



In making the analyses of the plants reported in Table III the 

 entire root system was ground and mixed previous to taking the 

 sample. From the figures just given it is seen that in order to make 

 these results comparable the size of the roots must be considered. 

 An approximate idea of the size can be obtained from the figures for 

 weight given in the table, the total weight of the roots of each plant 

 being given. For example, the extremely bitter White Top (No. 8) 

 weighed nearly 5 kilos and contained 0.03 per cent of hydrocyanic 

 acid, while another bitter variety, the Auntie Grace, contained 0.028 

 per cent, practically the same as the White Top, but weighed only 2.5 

 kilos. Had the Auntie Grace been as large as the White Top root it 

 might have been classed as a semibitter. 



In this group of thirt3 T -nine foreign varieties but two approach the 

 Florida Sweet in low content of hydrocyanic acid, these being Nos. 

 9690 and 9691 in the table. These were veiy large plants, weighing 

 4.1 and 5.3 kilos, respectively, while the Florida-grown plants of the 

 same weight would probably contain not more than 0.001 per cent. 



With the exception of the hydrocyanic acid content there is no 

 marked difference between the roots of the sweet and the bitter 

 varieties. The White Top has an unusually large and well-shaped 

 root, being similar to the Florida Sweet in shape and equally pala- 

 table. As shown in the table, it contains 55 per cent of starch, calcu- 

 lated to dr} T substance. In an examination made by the Bureau of 

 Chemistry of a large number of plants of the Florida Sweet variety 

 grown for the manufacture of starch the starch content ranged from 

 50 to 75 per cent of the dry substance. In the starch percentages 

 given in Table III there is about the same range. There appears to 

 be no relation between the starch and the hydrocyanic acid content. 



SEASON OF 1905. 



In the second year of the investigations at Biloxi the work was 

 devoted primarily to the development of seedlings, which phase of the 

 investigations was conducted by the Bureau of Plant Industry. It 



