470 
EDWARD F. WOODCOCK 
inally, and also causes the blades to extend nearly the whole distance 
around the inside of the seed as shown in figure 26. The starchy 
endosperm and the digestive aleurone layer have now become almost 
entirely depleted and the pressure of the enlarging cotyledons has 
collapsed the cells. Only the broken down remains of the aleurone 
layer are present inside the seed coat ; and in the folds of the cotyledons 
at their basal portion, appear the distorted, empty starch cells {fig. 27, 
EN). The rapidly enlarging cotyledons soon push off the wasted 
remains of the seed and unfold, becoming oriented in a horizontal 
position. These cotyledons present now very much the appearance 
of regular foliage leaves; they are equipped with chlorophyll and all 
the tissues typical of foliage leaves. 
Polygonella articulata 
An attempt made in the early part of March to find some of the 
seeds in the sand about the dead plants resulted in the finding of only 
already germinated seeds. The hypocotyl and radicle had attained 
a length of about 12 mm. A number of the seedlings were allowed to 
develop further in the laboratory in order to make a study of the later 
stages in germination. 
Upon CT umination of the earliest stages available conditions were 
found quite similar to those already described for Rumex crispus. 
At the stage shown by figure 28, the entire aleurone layer has become 
greatly enlarged. The cells in the thickened micropylar region show 
the characteristic granules of the digestive layer, while the remaining 
cells show a loose alveolar cytoplasm entirely free from granules. 
The enlarged condition of the aleurone cells causes the micropylar 
region of the layer to appear outside the seed coat {fig. 28, L) forming 
a collar-like structure as in Rumex crispus. This digestive layer 
behaves in a manner similar to that described in the preceding example. 
In the digestion of the starch there appears a marked difference, the 
starchy endosperm being depleted of its contents quite uniformly, 
instead of being progressive in its depletion. In contrast to Fago- 
pyrum and Rumex, the digestive starch is all used up by the germinat- 
ing embryo as it is absorbed, none of it is converted back into an 
insoluble form as in the above species. This digestion proceeds much 
slower than in the other species studied, consequently there is a 
corresponding slow growth of the young seedling. 
As this growth proceeds the cotyledons gradually increase in length 
