PREFACE 



Attempting an analytical review of a rapidly developing field is 

 rather like eating spaghetti with a spoon. In order to manage at 

 all, one has to cut some strands off short, while others elude one 

 altogether. This is so even though the total serving is not 

 unreasonably large; in 1961 the literature on electron-microscopic 

 structure of protozoa is still within the capacity of one reviewer. 

 The organisms known as protozoa include such a diversity of 

 types, however, that no two protozoologists (who are also diverse 

 organisms) approach them in quite the same way. 



In coping with this slippery prospect, I have emphasized details 

 that seem to me to be provocative or significant, and understated 

 or ignored others that to another critic may appear startling. 

 Inevitably, many of the questions raised in the following pages 

 are being answered through investigations now in progress; 

 certainly some of the answers will be apparent before the book 

 reaches its readers, and new problems not yet visualized will 

 be posed. 



But the yearning for an occasional summing-up is no less acute 

 because the field is in flux. Whether we approach the problem 

 as protozoologists (of whatever ilk), as evolutionists, or as cell 

 biologists, we should like to know whether results from ultra- 

 structure research suggest that the protozoan grade of organization 

 embodies any peculiar morphological features. Before the mush- 

 rooming quantity of data becomes too unmanageable, it is time 

 to stop and take a look. 



Although I have aimed at a complete coverage of the immediately 

 pertinent literature, there will be omissions, for which I express 

 my regret. Papers published in specialized journals of parasitology, 

 medicine, or botany are most likely to have escaped my attention. 

 Only a sampling has been included of taxonomic papers drawing 

 on electron microscopy for details of superficial structure as 

 criteria for species distinctions. Where information presented in 

 a preliminary report or abstract is repeated or amplified in a more 



