100 A GRAIN OF BARLEY. 
Completely enveloping the whole endosperm, we have the - 
remnant of the outer integument of the ovule, now forming 
the testa, or true envelope of the seed (Plate I., Figs. 1 
and 2, ¢, and Plate II., ¢.), and outside this again is the thin 
skin of the pericarp (fg in Plates I. and II.) which represents 
all that is left of the once thick-wailed ovary. We can now 
readily understand that the point of union of these two 
integuments, which is marked by the bright coloured “ pig- 
ment-string ” to which I have -previously referred, is really the 
remnant of the fuwmicle, the line of attachment of the ovule 
to the walls of the ovary. 
Outside the true grain we have the palee or glumes 
(Plate I. and II., 2.7. and g.s.) which only become adherent 
to the pericarp at a comparatively late stage of development. 
Thus we see that what we term the ‘ grain” of barley 
really includes the united product of both ovule and ovary: 
in other words it represents doth seed and fruit; the fruit 
portion, the product of the ovary, being reduced to a very 
thin integument. Such a combination of seed and fruit is 
called by botanists a caryopsis. 
Fig. 11, Plate IV., is a photo-micrograph of a section taken 
through the integuments of a barley-grain, and includes a small 
portion of the enclosed endosperm. Fig. 13, Plate V., 
represents a similar section of a wheat grain, but in the latter 
case the integuments consist only of testa and pericarp, the 
palee being non-adherent in the case of wheat. The 
rectangular cells, of which there are three rows in barley, but 
only a single row in wheat, are the “aleurone” cells, and 
they constitute the peripheral portion of the endosperm. I 
have already referred in general terms to the two essentially 
different kinds of cells of which the endosperm of ripe barley 
is made up, the starch-containing and the aleurone cells, but 
I must now describe them a little more in detail. The 
starch-containing cells are arranged with their larger dimen- 
sions parallel with the axis of the grain. When viewed in 
