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STUDIES ON THE PLANT CELL. VTIL 1 



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 : 



1. 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. 



4. The essential 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- 

 phyceae (blue-green algae), 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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