INTRODUCTION 



from it, are the subject of this book. Since representatives of most 

 of the major protozoan groups have been studied, it is possible to 

 outline a patchwork comparative anatomy. This will continue to 

 be patchwork for a long time, but a review now should point out 

 the gaps most conspicuously in need of filling. Moreover, by 

 assembling some of the remarkable facts of protozoan structure, 

 such a review may demonstrate to the cell biologist that the 

 educational value of the protozoa, as proclaimed above, is not 

 exaggerated. (For similar arguments from evangelists of bio- 

 chemical protozoology, see for example Hutner, 1961; Hutner 

 and Provasoli, 1951.) 



In what follows, the approach will be fundamentally evolu- 

 tionary, based on the proposition that all eucellular* life had a 

 common origin in a progressive moneran* stock. In agreement 

 with the majority of modern protozoologists (see Hyman, 1940; 

 Grasse, 1952) it is assumed that the phytoflagellates are the oldest 

 protozoa. Recently there has been a spate of thoughtful and often 

 elegant discussions of the origin of life and the mechanisms of 

 evolution (e.g., see Needham, 1959; Gaffron, 1960). Evolutionary 

 histories of many groups have been considered, but relatively few 

 novel speculations on the phylogeny of eucellular protists* have 

 been offered. The one explicit new theory is that of Dougherty 

 (1955) and Dougherty and Allen (1960), founded largely on 

 evidence from biochemistry. They suggest, in brief, that phyto- 

 flagellates arose from primitive red algae, which in turn derived 

 from blue-green algae (a similar idea is implied, but not discussed, 

 by Copeland, 1956). Evidence from electron-microscope studies 

 that bears on, and tends to support, this theory will be discussed 

 in Chapter 4. 



Arguments in favor of a common ancestry of eucells rest largely 

 on similarities in biochemistry and in the ultrastructure of common 

 organelles. An opposing point of view, based on the same 

 evidence, is held by Kerkut (1961) arid Grimstone (1959b, 1961). 



* The present usage of these terms, not original here, should be explained. 

 Monera (= bacteria and blue-green algae) and Protista (= Monera plus all 

 algae, fungi and protozoa) are used as defined most recently by Dougherty 

 and Allen (1958). Eucell (= cell provided with a membrane-limited nucleus 

 or eukaryon ([Dougherty, 1957a]); in other words, cells of all organisms 

 above the Monera) is used as proposed by Picken (1960). 



