PREFACE TO SECOND FASCICLE OF PART I. 

 INTRODUCTION AND PROTOZOA 



THE irregular publication of the parts of the Treatise on Zoology 

 is the inevitable result of the fact that it is the work of a 

 number of authors. 



I have determined not to allow Professor Minchin's most 

 timely and valuable treatise on the Sporozoa to lie by in the 

 printers' hands until the other sections of Part I. which 

 logically precede it are ready for the press ; and with this I have 

 been able to combine Dr. J. J. Lister's section on Foraminifera 

 (which contains much that is new and original), Professor 

 Hickson's section on Infusoria, and a section on the Structure 

 of Animal and Vegetable Cells, with especial reference to the 

 points which arise in the study of the Protozoa, by Professor 

 Farmer. 



These four sections form the second fascicle of the First 

 Part of this treatise ; the first fascicle, which is in preparation, 

 will contain an Introduction and descriptions of the Proteo- 

 myxa, Mycetozoa, Lobosa, Heliozoa, Labyrinthulidea, Radio- 

 laria, and Flagellata, forming sections A to G of Chapter I. 

 The Protozoa. 



The division of the work into Chapters, of which the 

 second to the twenty -first are already published, has resulted 

 in a somewhat awkward restriction of the Protozoa to nominally 



