INTRODUCTION. XXXll 
given individual or species ; it carries us back some 
stages further im the history of particular organisms, 
but so also does teratology. Many cases of arrest of 
development show the mode of growth and evolution 
more distinctly, and with much greater ease to the 
observer, than does the investigation of the evolution of 
organs under natural circumstances. Organogeny by 
no means necessarily, or always, gives us an insight into 
the principles regulating the construction of flowers in 
general. It gives us no archetype except in those 
comparatively rare cases where primordial symmetry 
and regularity exist. When an explanation of the 
irregularity of development in these early stages of 
the plant’s history is required, recourse must be had 
to the inferences and deductions drawn from tera- 
tological investigations and from the comparative 
study of allied forms precisely as in the case of adult 
flowers. 
The study of development is of the highest import- 
ance in the examination of plants .as individuals, but 
in regard to comparative anatomy and morphology, 
and specially in its relation to the study of vegetable 
homology it has no superiority over teratology. Those 
who hold the contrary opinion do so, apparently, be-— 
cause they overlook the fact that there is no distinction, 
save of degree, to be drawn between the laws regulating 
normal organisation, and those by which so-called 
abnormal formations are regulated. 
It is sometimes said, and not wholly without truth, 
that teratology, as it.stands at present, is little more 
than a record of facts, but in proportion as the laws 
that regulate normal growth are better understood, 
so will the knowledge of those that govern the so- 
called monstrous formations increase. Sufticient has 
c 
