PREFACE. XI 



setting up a finger-post, so to say, to direct the inquirer into the wider 

 road. In the section of the work devoted to the very minute portion 

 of creation, he has ventured to dwell somewhat longer upon the sub- 

 ject, in the belief that that department is more especially the province 

 of the microscopist than many others. He has arranged his topics 

 under special headings, and in separate chapters, for the sake of greater 

 clearness and precision ; and has brought the ever-welcome aid of illus- 

 trations to convey his explanatory remarks more vividly to the minds 

 of his readers. To his frierid, Mr. J. G. Kelly, he has to express his 

 thanks for valuable assistance afforded in making drawings of the ob- 

 jects from the microscope and camera lueida; as also to Mr. George 

 Pearson, for the admirable manner in which he has engraved them. 

 The author has minutely described the use and manipulations of the 

 Microscope, so as to render its management, he ventures to hope, intel- 

 ligible to all ; and his marked and warm acknowledgments are due to 

 the eminent maker and improver of the Microscope, Mr. Boss, for his 

 revision of this portion of the work. He is peculiarly indebted to Pro- 

 fessor John Qnekett, whose very valuable lectures, delivered in the 

 Eoyal College of Surgeons, and other multifarious and successful re- 

 searches, have pre-eminently distinguished him as the microscopist of 

 the day. From notes made at the lectures spoken of, and from the 

 many admirable ' papers which this gentleman has published, much 

 sound information has been gleaned ■ and the author has to thank him, 

 in the most sincere and cordial manner, for the ready acquiescence that 

 he gave to the writer's wish to cull from the choicest of the mass of 

 contributions with which he has enriched microscopical science. The 

 author has also freely availed himself of the researches of other scien- 

 tific investigators, — Leeuwenhoek, Ehrenberg, Carpenter, Johnston, 

 Balfs, Busk, Gosse, Hassall, and the members of the Microscopical 

 Society of London, to the foundation of which excellent society we may 

 ascribe the rise and progress of many improvements in the instrument ; 

 and it has tended, moreover, to stimulate discoveries, and induce greater 

 accuracy of observation. 



