THE CELL THEORY 243 
Schleiden was educated as a lawyer, and began the prac- 
tice of that profession, but his taste for natural science was 
so pronounced that when he was twenty-seven years old 
he deserted law, and went back to the university to study 
medicine. After graduating in medicine, he devoted himself 
mainly to botany. He saw clearly that the greatest thing 
needed for the advancement of scientific botany was a study 
of plant organization from the standpoint of development. 
Accordingly he entered upon this work, and, in 1837, arrived 
at a new view regarding the origin of plant cells. It must 
be confessed that this new view was founded on erroneous 
observations and conclusions, but it was revolutionary, and 
served to provoke discussion and to awaken observation. 
This was a characteristic feature of Schleiden’s influence upon 
botany. His work acted as a ferment in bringing about new 
activity. 
The discovery of the nucleus in plant cells by Robert 
Brown in 1831 was an important preliminary step to the work 
of Schleiden, since the latter seized upon the nucleus as the 
starting-point of new cells. He changed the name of the 
nucleus to cytoblast, and supposed that the new cell started 
as a small clear bubble on one side of the nucleus, and by 
continued expansion grew into the cell, the nucleus, or 
cytoblast, becoming encased in the cell-wall. All this was 
shown by Nageli and other botanists to be wrong; yet, curi- 
ously enough, it was through the help of these false observa- 
tions that Schwann arrived at his general conclusions. 
Schleiden was acquainted with Schwann, and in October, 
1838, while the two were dining together, he told Schwann 
about his observations and theories. He mentioned in par- 
ticular the nucleus and its relationship to the other parts of 
the cell. Schwann was immediately struck with the simi- 
larity between the observations of Schleiden and certain of his 
own upon animal tissues. Together they went to his labo- 
