PEITCHARDj ON INFUSORIA. 55 



scale, to em'brace the whole of the then known microscopic 

 world, at the present time anything like a sufficient view 

 of it, even in a general sense, requires the concurrence of 

 several observers, each of whom has made a particular depart- 

 ment in it the subject of his special attention. TJie present 

 work is a favorable instance of what may be effected by this 

 scientific co-operation. 



The work is divided into two parts ; the former comprising 

 a " General History," and the second a " Systematic History, 

 of the Infusoria," as they are termed. But this term, it must 

 be understood, is here used in a wider sense than that in which 

 it is now usually accepted. Mr. Pritchard, we presume, 

 for the sake of keeping up a uniformity of title with the former 

 editions of the work, retains the term " Infusoria" in the wide 

 or Ehrenbergian sense; whilst most recent writers confine it to 

 a particular class or division of the rather vague sub-kingdom 

 Protozoa, corresponding pretty nearly with the " sub-section" 

 here (p. 266) termed Oiliata. The necessity of adhering so 

 closely to the old title of the work may, in a commercial 

 point of view, have been considered imperative, but in a 

 scientific, it is much to be regretted ; for in science — and this 

 applies as strongly to science presented in a popular form as 

 in a more rigid guise — precision in the use of terms, it is 

 perhaps needless to insist, is of the utmost importance. The 

 Infusoria, then, as the term is here employed, are sub- 

 divided into — l,Bacillaria; 2,Phytozoa; 3, Protozoa; 4, Rota- 

 toria, or Rotifera ; and 5, Tardigrada ; and the mere sight of 

 these names is sufficient to show the confusion that must 

 arise in the non-scientific mind, when it finds organisms of 

 such extreme diversity embraced under any common term, 

 and especially when it discovers that that term has, within a 

 few years, been employed to distinguish a group of organisms 

 regarded almost as an equivalent to a sub-kingdom of animals. 

 In this sense it has long been discarded by all naturalists, and 

 it is much to be regretted, as it appears to us, that a work so 

 deservedly popular as the present will undoubtedly become 

 should have a tendency, from the want of due explanation, to 

 perpetuate a grievous error. 



With respect to the mode in which the dififerent sections 

 of the work have been elaborated by the respective editors 

 or authors, as they might properly be termed, we can 

 only repeat that it is in the highest degree satisfactory. 

 The care and judgment with which the most recent 

 observations and views have been collected, condensed, and 

 in many instances commented upon, are deserving of the 

 highest commendation. A-ud as regards the general arrange- 



