XiV¥ AUTHOR'S PREFACE. 
these observations of Dumortier, in as much as they regard the 
tissue consisting of cells as the yelk and not the liver. (Bulletin 
de l’Acad. royale de Bruxelles, tom. v, No. 5.) 
Other instances of the resemblance in form between different 
animal tissues and those of vegetables had already been 
repeatedly pointed out. Thus it was frequently said, in refer- 
ence to thickly-crowded animal cells, or even mere globules, 
that they presented an appearance resembling vegetable cellu- 
lar-tissue ; and Valentin (Nov. Act. N. C. xvui, P. 1, 96), 
after describing the nucleus of the epidermal cells, states that 
it reminded him of the nucleus which occurs in the vegetable 
kingdom, in the cells of the epidermis, the pistil, &. Nothing, 
however, resulted from such comparisons, because they were 
mere similarities in figure, between structures which present 
the greatest variety of form. 
Schleiden instituted researches into the mode of development 
of vegetable cells, which illustrated the process most excellently. 
This admirable work appeared subsequently in the second part 
of Miiller’s Archiv for 1838. He found, that in the forma- 
tion of vegetable cells, small, sharply-defined granules are first 
generated in a granulous substance, and around them the cell- 
nuclei (cytoblasts) are formed, which appear like granulous 
coagulations around the granules. The cytoblasts grow for a 
certain time, and then a minute transparent vesicle rises upon 
them, the young cell, so that, in the first instance, it is placed 
upon the cytoblast, like a watch-glass upon a watch. It then 
becomes expanded by growth. Schleiden communicated the 
results of his investigations to me, previous to their publication 
in October, 1837. The resemblance in form, which the chorda 
dorsalis, to which J. Miiller had already drawn attention, and 
the branchial cartilage of the tadpole present to vegetable cells, 
had previously struck me, but nothing resulted from it. The 
discoveries of Schleiden, however, led to more extended re- 
searches in another direction. 
