20 
Saunders . — On the Structure and 
Corresponding local modifications are much less marked 
when the gland is examined vertically. In the neck, how- 
ever, there is a somewhat sudden alteration in the structural 
features of the epidermal cells ; they lose their special secretory 
characters, and do not differ from ordinary epidermal cells. 
The external wall does not undergo mucilaginous degenera- 
tion, and possesses a distinct cuticle, which at the mouth of 
the gland is continuous with that of the ovary-wall. There 
is no deposition of starch, and no characteristic meshwork ; 
the nucleus is generally central, and except in quite young 
cells the protoplasm is scanty, and contains a few large 
vacuoles. 
Probably all, or nearly all, the cells of a gland pass through 
the whole series of changes above described, yet these changes 
do not always occur simultaneously in the cells. This is 
shown by the fact that in any section of a gland the cells are 
not all found in the same stage of activity, a condition of 
things particularly obvious in flowers in which the gland-cells 
have been fairly active, and in which the slight differences 
present in the earlier stages have had time to accumulate. 
Thus a section, in which the majority of the epidermal gland- 
cells are passing through the meshwork stage, is sure to con- 
tain some which have already reached the final stage, with 
parietal nucleus, large central vacuole, and no meshwork ; 
while in others starch may be present, and the meshwork not 
yet apparent. In consequence of this unequal manifestation 
of activity, no one particular stage of the secreting cells can 
be said to be coincident with, and entirely confined to, one 
particular stage in the development of the flower. At the 
same time that appearance which is most common among 
the gland-cells at any one stage of the flower may be regarded 
as £ typical ’ of that stage, it being always understood that 
cells exhibiting those stages which precede and follow the 
typical one may be, and generally are, present as well. 
The following table indicates those characters of the gland- 
cells which are typical of the various stages in the develop- 
ment of the flower : — 
