tle importance seems to be attached to it that the
appearance is not always referred to in the explanations of the figures
in which it is represented. Mr. Bauer, however, who has also figured
it in the utriculi of the stigma of Bletia Tankervilliae has more
particularly noticed it, and seems to consider it as only visible after
impregnation."(2)

SCHLEIDEN AND SCHWANN AND THE CELL THEORY

That this newly recognized structure must be important in the economy of
the cell was recognized by Brown himself, and by the celebrated German
Meyen, who dealt with it in his work on vegetable physiology, published
not long afterwards; but it remained for another German, the professor
of botany in the University of Jena, Dr. M. J. Schleiden, to bring the
nucleus to popular attention, and to assert its all-importance in the
economy of the cell.

Schleiden freely acknowledged his indebtedness to Brown for first
knowledge of the nucleus, but he soon carried his studies of that
structure far beyond those of its discoverer. He came to believe that
the nucleus is really the most important portion of the cell, in that
it is the original structure from which the remainder of the cell is
developed. Hence he named it the cytoblast. He outlined his views in
an epochal paper published in Muller's Archives in 1838, under title of
"Beitrage zur Phytogenesis." This paper is in itself of value, yet the
most important outgrowth of Schleiden's observations of the nucleus did
not spring from his own labors, but from those of a friend to whom he
mentioned his discoveries the year previous to their publication.
This friend was Dr. Theodor Schwann, professor of physiology in the
University of Louvain.

At the moment when these observations were communicated to him Schwann
was puzzling over certain details of animal histology which he could
not clearly explain. His great teacher, Johannes Muller, had called
attention to the strange resemblance to vegetable cells shown by certain
cells of the chorda dorsalis (the embryonic cord from which the spinal
column is developed), and Schwann himself had discovered a corresponding
similarity in the branchial cartilage of a tadpole. Then, too, the
researches of Friedrich Henle had shown that the particles that make up
the epidermis of animals are very cell-like in appearance. Indeed, the
cell-like character of certain animal tissues had come to be matter of
common note among students of minute anatomy. Schwann fe