Bui. 27, Porto Rico Agr. Expt. Station. 
Plate IV. 
Fig. I.— Result of Experiment in Spacing Plantings of Potato Yams. 
Pile on Right, 4 by 4 Feet; on Left, 2 by 2 Feet. 
Fig. 2.— A Hill of Tongo Yams (Dioscorea aculeata). S. P. I. No. 31923. 
