THE SWEET POTATO. 69 



aud thickness of the vines, their exact color near the 

 tip, the center, the base, on top, and below; the size 

 of the leaves, the color of young and old leaves, the 

 length of the petiole, the amount of hairiness on 

 leaves and stem, the coloration of the veins on both 

 upper and lower surface, the amount of latex, etc. 

 After the harvest the tubers were studied in regard 

 to size, shape, exterior color, distrilmtion and size 

 of lenticels, roots, and shoots, hardness when raw, 

 color of flesh, wood elements, and caml)ium, and 

 relative abundance of latex. Samples were boiled 

 and baked of all varieties of which there was mate- 

 rial to spare, and observations made on the color, 

 odor, softness, flavor, sweetness, and stringiness of 

 the cooked tubers. 



The great difference in the outer appearance ot 

 foliage, stems, and tubers suggested corresponding 

 ditferences in their internal structure, and to deter- 

 mine the extent of such differences, slides were 

 prepared from fifteen varieties which could easily be 

 disting-uished, showing the following parts: Upper 

 and lower epidermis of leaf, cross-sections through 

 the leaf, petiolar nectaries, petiole, the tip and base 

 of a full-grown stem, and the upper and lower part 

 of a tuber, and longitudinal sections through the 



stem. 



During the winter the writer received an abun- 

 dance of material from the already named stations 

 and also from Jamaica, India. Barbadoes, the Sand- 

 wich Islands, Mauritius, and Colombia. As many of 

 the tubers were in a rather poor condition on arrival, 

 the only way to save them was to plant them at 

 once. Accordingly all the tubers were started in the 

 greenhouses of the Botanical Garden of the Uni- 

 versity of Pennsylvania, and the entire lot planted 



