6 ARRANGEMENT OF ORGANS. 
established, though in matters of detail much remains 
to be cleared up, even in such important points as the 
share which the axis takes in the construction of the 
flower and fruit, the nature of the placenta, the con- 
struction of the ovules, and other points. 
The facts already known justify the adoption of a 
standard or typical arrangement as just mentioned. 
The intrinsic value of this type is shown by the facility 
with which all varieties of form or arrangement may 
be explained by reference to certain modifications of it. 
It must, however, be considered as an abstraction, and 
should be looked on in the heht rather of a scaffolding, 
which enables us to see the buildme and its several 
parts, than of the edifice itself, but which latter, from 
our imperfect knowledge and limited powers, we could 
not see without some such assistance. 
The typical form may be, hypothetically at least, con- 
sidered as the primitive one transmitted by hereditary 
descent from generation to generation, and modified to 
suit the requirements of the individual, or in accord- 
ance with circumstances. If it be borne in mind that 
it is but an artificial contrivance, more or less true— 
a means to an end, and not the end itself—no harm 
will arise from its employment; and as knowledge 
increases, or as circumstances demand, the hypo- 
thetical type can be replaced by another more in 
accordance with the actual state of science. 
Teratological changes in the arrangement of organs 
depend upon arrest of growth, as when parts usually 
spirally arranged remain verticillate, owimg to the 
non-development of the internodes, or to excessive 
erowth, or development ; but in many utstances it is 
