by them, and used to construct their own thickening tissue.

15. Next, I take Balfour's 'Structural Botany,' and by his index, under the
word 'Pith,' am referred to his articles 8, 72, and 75. In article 8,
neither the word pith, nor any expression alluding to it, occurs.

In article 72, the stem of an outlaid tree is defined as consisting of
'pith, fibro-vascular and [42] woody tissue, medullary rays, bark, and
epidermis.'

A more detailed statement follows, illustrated by a figure surrounded by
twenty-three letters--namely, two _b_ s, three _c_ s, four _e_ s, three _f_
s, one _l_, four _m_ s, three _p_ s, one _r_, and two _v_ s.

Eighteen or twenty minute sputters of dots may, with a good lens, be
discerned to proceed from this alphabet, and to stop at various points, or
lose themselves in the texture, of the represented wood. And, knowing now
something of the matter beforehand, guessing a little more, and gleaning
the rest with my finest glass, I achieve the elucidation of the figure, to
the following extent, explicable without letters at all, by my more simple
drawing, Figure 25.

16. (1) The inner circle full of little cells, diminishing in size towards
the outside, represents the pith, 'very large at this period of the
growth'--(the first year, we are told in next page,) and 'very large'--he
means in proportion to the rest of the branch. _How_ large he does not say,
in his text, but states, in his note, that the figure is magnified 26
diameters. I have drawn mine by the more convenient multiplier of 30, and
given the real size at B, _according to Balfour_:--but without believing
him to be right. I never saw a maple stem of the first year so small.