III. THE STRUCTURE OF IPOMCEA 

 BATATAS. 



In the following is given a detailed description of 

 macroscopical and microscopical characters of 

 Ipomoea Batatas. When the macroscopic charac- 

 ters varied with the varieties, that has been stated; 

 where differences were found in the microscopic 

 structure of different varieties, that was also 

 recorded, but the writer wishes it to be understood 

 that the material studied microscopically was not 

 abundant enough to justify him in saying that the 

 special characters found in particular varieties are 

 typical of them. 



For the sake of convenience the plant is consid- 

 ered under the headings of Root, Stem, and Leaf. 



(A) Root (Figs. 21-26) : Springing from two sides 

 of a stem at every joint, and from five longitudinal 

 rows on tubers, which are usually more or less dis- 

 arranged ; wliite, yellowish, pink or purple, long and 

 of uniform diameter for a shorter or longer distance, 

 until thickened into a tuber. Tuber fascicular to 

 spherical, smooth or veiny, terete or 5, 4, or 6-lobed 

 in cross-section, with roots coming off in 5, 4, or 6 

 longitudinal rows, or apparently irregularly; with 

 large conspicuous or small inconspicuous lenticels, 

 with dormant shoots usually near the lenticels and 

 root traces, but often apparently irregularly placed. 

 Shoots sprout earliest at proximal end of tuber, 

 breaking through skin, later in centre and distal end. 

 Color of tuber, white, yellowish-white, pinkish-white, 



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