X PREFACE. 



ready and valuable assistance in working out the voluminous and, in many 

 cases, exceedingly intricate bibliography of the present subject. He has 

 also to record his high appreciation of the accurate and highly artistic 

 manner in which Mr. W. Rhein has reproduced on stone the drawings for 

 the plates committed to his care. 



For an abundant supply of living material for investigation, much of 

 which has been utilized in the record of new data, and for the illustration 

 of this Manual, the best thanks are due from the author to Mr. Thomas 

 Bolton of Birmingham, and to Mr. John Hood of Dundee. 



Lastly, but not leastly, the author has to acknowledge his great indebt- 

 edness to the Council of the Royal Society, through whose recommendation 

 a grant from the Government Fund for the Promotion of Scientific Research 

 has been on several occasions allotted him, thus assisting him with the 

 means of obtaining the necessary costly microscopical apparatus, and of 

 devoting that time to original research, without which the prolonged 

 investigations recorded in this treatise, more especially in connection with 

 the Flagelliferous Infusoria, could scarcely have been accomplished. 



LONDON, May 1882. 



