382 
HEBER W. YOUNGKEN 
Histology 
When examined microscopically, sections of the Trinidad dasheen corm, 
passing from the periphery toward the center, show the following histological 
peculiarities : 
1. A zone of cork composed of numerous layers of cells with suberized walls, varying 
in size from irregular polygonal to rectangular. 
2. A broad zone of phellogen, composed of more or less rectangular, tangentially elon- 
gated cells with rich protoplasmic contents. 
3. A broad central matrix composed of parenchyma, the cells of which are mostly 
thin-walled and abundantly filled with starch. The starch grains are mostly simple, but 
compound grains composed of as many as eight units are occasionally met with. The 
Fig. 3. Two mother corms with their lateral cormels, the product of an eleven-pound hill 
of Trinidad dasheens (photo, by R. A. Young). 
simple grains vary in outline from rounded to irregularly rounded to irregularly ovate or 
angular. Some of these are devoid of striations or distinct hilum, while others show both of 
these structures. In size, they range from 3 m to 19.2 n. The hilum, when distinct, varies 
from linear to circular to angular to several-cleft. The lamellae and striations, when dis- 
tinct, are always concentric. These, as well as the hilum, may be well observed in a mount 
stained with dilute gentian violet. Scattered throughout this region are to be noted nu- 
merous mucilage reservoirs of irregularly rounded, oval or ellipsoidal outline, whose contents 
are deeply stained with basic aniline dyes. The fibrovascular bundles are of concentric 
type and may be found scattered throughout the section in irregular fashion. From the 
main axis bundles, numerous branch bundles emanate at various levels, which course out 
into the lateral cormels. Crystals of calcium oxalate are found in numerous cells of the 
central matrix in the form of raphides. 
