The causes of the slowness of the progress in expressing in articulate
words what is understood and desired, on the part of normal children, is
not, however, to be attributed, as it has often been, to a slower
development of the expressive motor mechanism, but must be looked for in
the difficulty of establishing the connection of the various central
storehouses of sense-impressions with the intercentral path of
connection between the acoustic speech-centers and the speech-motorium.
For the purely peripheral articulatory acts are long since perfect,
although as yet a simple "_a_" or "_pa_" can not be repeated after
another person; for these and other sounds and syllables are already
uttered correctly by the child himself.

The order of succession in which these separate sounds appear, without
instruction, is very different in individual cases. With my boy, who
learned to speak rather late, and was not occupied with learning by
heart, the following was the order of the perfectly pure sounds heard by
me:

On the left are the sounds or syllables indicated by one letter; on the
right, the same indicated by more than one letter; and it is to be borne
in mind that the child needs to pronounce only fourteen of the nineteen
so-called consonants of the German alphabet in order to master the
remaining five also; for

c = ts and k
v = f and w
x = ks and gs
q = ku and kw
z = ts and ds

and of the fourteen four require no new articulation, because

p is a toneless b
t is a toneless d
f is a toneless w
k is a toneless g

Of the ten positions of the mouth required for all the consonants of the
alphabet, nine are taken by the child within the first six months:*

Months.
1. Indefinite
vowels; ae u, uae.
2. a, oe, o; m,
g, r, t; h, am, ma, ta, hu, oer, roe, ar, ra, goe.
3. i; b, l, n, ua, oa, ao, ai, [(ei], oae, aeo, aea, aeoe; oem, in, ab,
om; la, ho, moe, nae, na, ha, bu; ng, mb, gr.
4. e, [(aeu], a-u, aoe, ea; an; na, toe, la, me; nt.
5. ue (y); k, ag, eg, ek, ge, koe.
6. j; the oi ([(eu], [(aeu]), io, oee, eu (French); ij, aj,
lingual-labial oeg, ich; ja, jae; rg, br, ch.
sound,
7. d, p, aee, ui; mae.
8. eoe, ae, ou, [(au]; up; hoe, mi, te.
9. ap, ach, aem; pa, ga, cha.
10. el, ab,