Embryo and A leurone Layer of Hordenm . 1171 
amylo- and cytoclastic action so much as to note what ultimately happens 
to the walls and to the starch storage contents of the amyliferous cells 
during periods ranging from 1 to 4 weeks. 
Under the conditions described, the enzymes in play having, free 
access to the starch granules in those parts where the plane of section 
literally divided the endospermic cells into halves and thus exposed their 
starch contents, solution of starch invariably appeared to precede, in point 
of time, action on the cell walls ; the latter, however, were distinctly swollen 
at this juncture and difficult to stain with either Congo red or Bismarck 
brown. 
The embryo and aleurone layer do not attack the material at their 
disposal at equal rates—the action of the former on both starch and cell 
walls being at all stages of the experiment earlier, the reason being, as 
already insisted in the discussion of various experiments with fragments of 
the aleurone layer, that an isolated non-growing 1 fragment of secretory 
tissue does not, as anticipation would lead one to expect, comport itself in 
any way comparable with that manifested by an organism like the embryo. 
At an early stage, 2-3 days, examination of the sections placed under 
embryos invariably shows that marked corrosion of starch granules 
characteristic of the action of the amylase which it secretes, and simul¬ 
taneously the cell walls of the section acquire a swollen, hyaline appearance. 
Later, 4-7 days, the section may be practically depleted of its starch con¬ 
tents and the cell walls broken up into spindle-shaped fragments of varying 
size. A little later these are digested, and then, if care is taken not to dis¬ 
turb the section, after cautious warming of the gelatine and allowing it to 
reset the section is literally reduced to a diagrammatic representation 
of the cytoplasmic network of each cell divested of its original cell walls 
and inclusions. The parts of the diagram previously filled in by the cell 
walls are now clear spaces. Gentle flooding of the preparation-with Congo 
red or Bismarck brown, both of which admittedly stain cellulosic structures, 
and subsequent cautious removal of the excess of stain merely result 
in the staining and rendering more easily visible of the meagre cytoplasmic 
network ; that portion of the section formerly occupied by the cell walls 
remains unstained, showing that the appearances described are not due to 
optical properties of any presumed residual matter. At a still later epoch, 
7-14 days or longer, the network disappears, portions undergoing dis¬ 
integration presenting a beaded appearance, and the organized structure 
noted during the period immediately preceding this phase gradually 
disappears ; the network is reduced to a structureless mass of debris. 
Finally it is to be noted that the aleurone layer included in the 
section entirely resists disintegration. 
1 Repeated examination of the microtomed stained section of the aleurone layer prepared from 
germinating seeds at various stages fails to reveal any distinct signs of nuclear or cell division. 
