ii8 



surface, were found to be wliite and mealy, wliile f»n the s^lassy ])laces there 

 was only a slight reaction. 



The glutinous layer in the Mecklenburg grain was not developed at all, 

 the thin seed shell only incompletely. In place of this glutinous layer (Fig. 

 12 k) a plate-like parenchyma was found, the content of which did not 

 differ essentially from that of the underlying tissue. 



The most striking thing connected with this abnormal wlieat grain was, 

 however, the position of the embryo on the opposite end from that which 

 bore the roots (Fig. 12 w) and exactly in the middle of the grain (as in 

 Typhaceae) equally surrounded on all sides by the tissue of the starch- 

 containing endosperm. While in the normally constructed wheat grain the 

 seedling lies without, at the base of the grain, and is connected with the 

 endosperm by a special organ, the scutellum (the cotyledon), the seedling 

 lies here (Fig. 12 e) without cotyledons in a central cavity (Fig. 12 h) of 

 the grain. 



This cavity in some of the grains is elliptical, in others triangular. In 

 some it extends possibly to the middle of the grain, in others, becoming 

 narrower and narrower toward the top, it reaches to the tip, even penetrating 

 into the tissue of the cap. On the inner side it is lined with a layer formed 

 of two plate-like rows of cells of a glutinous content (Fig. 12 a) which 

 clearly resembles the glutinous layer deposited in healthy grains outside the 

 endosperm. 



The young leaves of the seedling, folded over one another, show no 

 essential variation. On the contrary, the number of secondary roots formed 

 in whorls at almost equal distances (Fig. 12 r) steadily increases up to 6 to 8 

 and these roots appear to be covered by a parenchymatous layer arranged in 

 the manner of cork cells, 6 to 8 cells thick and free from starch. 



On this tissue lies the combined and modified seed coat (Fig. 12 sf) 

 which in dry grain becomes thicker walled with more abundant cells toward 

 the tip and develops imperceptibly into the cap which the root bears at its 

 tip (Fig. 12 w). 



The vascular bundle is continued into the cap from the roots. Here are 

 often found several bundles united at the tip of the cap into a ring-like, 

 thicker network of ducts running horizontally and resembling a node of the 

 stalk. 



Still further back from the tip these vascular bundles (Fig. 12 g), iso- 

 lated near the outer edge of the inside of the cap, are seen to run backward 

 (Fig. 12 gg). The endosperm normally has no fully developed vascular 

 bundles and the cotyledons only embrj^onic ones. Here, however, the vas- 

 cular bundles take an often irregular course through the endosperm and, 

 in the individual grains, surround the seedling in a semi-circle and have 

 not developed even though the grains lay in the soil over winter. 



By cutting cross-sections from the diseased grains and submitting 

 them to microscopic investigation, the probable cause of this striking mal- 



