Ehrenbergii, Supp. Plate XXXI. fig. 356, and on that occasion
an admirable photograph of the object left me no room for hesitation
as to the species intended. To avoid confusion and uncertainty
in the synonyms, I have also abstained from recording
written descriptions, and the references in every case, not otherwise
stated, are to the numbers of the plate and figure in the
work quoted; and, to preserve uniformity, I have invariably
used letters for the plate, and numerals for the figure.
It will be seen that I have omitted all mention of the genus
Bictyocha, whose forms, familiar to the English collector, have
hitherto been classed with the objects described in the present
work. This organism has, however, little in common with the
true Diatomaceae, and the position and structure of its siliceous
skeleton altogether exclude it from the class.
I have been obliged to defer, until the completion of the plates,
all explanation respecting the important function of Reproduction
in the Diatomaceae, and a detailed examination of the controversy
respecting the animal or vegetable nature of these organisms
; neither of these subjects could have been fully discussed
without a reference to many of the figures to be given in my
second volume, and I have thought it better to postpone these
topics, however immediately interesting, than to enter upon
explanations that must necessarily have been imperfect or unintelligible.
CONTENTS OE THE INTRODUCTION.
S e c t i o n I. The Habitats and general Appearance of the Diato
m a c e s e ................................................................... xi
II. Structure of the Siliceous Epiderm of the Diatomaceous
Frustule................................................................... xiv
III. Internal Structure and Cell-contents of the Diatomaceous
Frustule..............................................................xix
IV. Movements of the Dia tom a ce se ..................................... xxii
V. Self-division in the Diatomaceae.................................... xxiv
VI. Terminology and Classification....................................xxvii
VII. On Collecting and Preserving Specimens of the Diatomaceae............................................................................
xxix