STUDIES ON THE PLANT CELL. .— VII. 
BRADLEY MOORE DAVIS. 
SECTION VI. COMPARATIVE MORPHOLOGY AND PHYSIOLOGY 
OF THE PLANT CELL. 
WE shall devote this section to the discussion of a number of 
topics some of which have received brief mention in the pre- 
ceding papers of the series but with other.subjects will now 
be considered in some detail. The material will be treated un- 
der the following five headings : — 
I. The simplest types of plant cells. 
2. Comparisons of the structures of some higher types of 
plant cell with simpler conditions. 
3. Some apparent tendencies in the evolution of mitotic phe- 
nomena. 
Ac The diemii structures of the plant cell and their be- 
havior in ontogeny. 
5. The balance of nuclear and cytoplasmic activities in the 
plant cell. 
I. THE SiMPLEST Types OF PLANT CELLS. 
There are three groups of plants which are conspicuous for 
the simplicity of their cell structure. They are: the Cyano- 
phycez (blue-green alga), Schizomycetes (bacteria) and the 
Saccharomycetes (yeasts). All three groups have received 
much attention and there has accumulated an extensive litera- 
ture which we shall not attempt to treat in detail, since it has 
. been handled very fully by the specialists in these subjects. 
We shall, however, present the most important conclusions and 
1 This paper concludes the series of studies on the plant cell. The author has 
a number of complete sets of reprints of this and the earlier sections. Enquiries 
may be addressed to Professor Bradley M. Davis, University of Chicago. 
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