XXXVl INTRODUCTION. 
use of students in most departments of biology. It 
will suffice to allude, in support of these statements, 
to the writings of Mr. Darwin on such subjects 
as rudimentary organs, the use or disuse of certain 
parts according to circumstances, the frequently ob- 
served tendency of some flowers to become structurally 
unisexual, the lability of other flowers perfectly 
organised to become functionally imperfect, at least 
so far as any reciprocal action of the organs of the 
same flower is concerned, reversions, classification, 
general morphology, and other subjects handled at 
once with such comprehensive breadth and minute 
accuracy of detail by our great physiologist. 
In the following pages alterations of function, unless 
attended by corresponding alterations of form, are 
either only incidentally alluded to, or are wholly passed 
over; such, for imstance, as alterations in the period 
of flowering, in the duration of the several organs, and 
so forth.t Pathological changes, lesions caused by 
insect puncture or other causes, also find no place in 
this book, unless the changes are of such a character 
as to admit of definite comparison with normal con- 
formation. Usually such changes are entirely hetero- 
morphous, and, as it were, foreign to the natural 
organisation. 
The practical applications of teratology deserve 
the attention of those cultivators who are concerned 
in the embellishment of our gardens and the supply 
! A curious illustration of the latter class of alterations came under 
the writer’s notice last summer (1868), and which he has reason to 
believe has not been previously recorded, viz. the persistence in an 
unwithered state of the petals at the base of the ripe fruit, in a straw- 
berry. All the fruits on the particular plants alluded to were thus 
provided as it were with a white frill. Whether this be a constant 
occurrence in the particular variety is not known. 
