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IX. Infusoria : What are they ? Their Collection and 



Investigation. 



By W. Saville Kent, F.L.S., F.Z.S., F.K.M.S. 



[An Address delivered at the Field Meeting held at Chigwell, June 25th, 



1881.] 



It has been my privilege to accompany you this afternoon 

 in your pleasant Field Meeting in the search for microscopic 

 spoils, and more particularly to assist you, so far as circum- 

 stances would permit, in the collection of the special objects 

 of my investigation, namely, Infusoria. 



Although Jupiter Pluvius has unfortunately been so unpro- 

 propitious as to seriously interfere with our good intentions, 

 I yet purpose now to addi'ess you briefly upon the more 

 important features of this highly interesting organic group, 

 trusting that the remarks I make may induce some, or, 

 I would even hope, many, members of the Essex Field Club 

 to embark also upon its systematic study. 



It is in the first place desirable that I should place before 

 you a concise definition of the series of organisms that, in 

 accordance with our present knowledge, have to be included 

 within the Infusorial world, such definition being requisite to 

 enable the student to know what to accept and what to reject 

 from among the multifarious forms that w^U present them- 

 selves to his notice at the very outset of his investigations, 

 and which were actually comprised in the group by the 

 earher authorities. Even the latest complete treatise in the 

 English language, Pritchard's ' History of the Infusoria,' 

 that relates to this organic group, is based upon the lines 

 laid down half a century ago by C. E. Ehrenberg, and 

 includes, in a similar manner, a heterogeneous assemblage of 

 animal and vegetal organisms belonging to half a dozen or 

 more distinct classes (Diatoms, Desmids, Rotifers, Rhizopods, 



