O. F. MULLER, 1773-1786. I 5 



ledge of the larger forms of animalcules, chiefly Vorticellidae and Stentoridse, 

 preceding the appearance of what to the present day holds rank as the 

 earliest standard work that embodies a complete and systematic account of 

 tlie members of the infusorial world. Reference is here made to the 

 'Animalcula Infusoria' of Otho Friedrich Muller, a posthumous quarto 

 volume published in the year 1786, containing no less than fifty plates and 

 367 pages of letterpress devoted to the description and illustration of close 

 upon three hundred species, fluviatile and marine, investigated and drawn 

 from the life by this indefatigable worker during a period extending over 

 no less than twenty years. 



This early pioneer in the then terra incognita of the Protozoic 

 sub-kingdom had already in his 'Vermium terrestrium et fluviatilium 

 succincta Historia,' ' Zoologica Danicae Prodromus,' and ' Zool. Dan. Icones,' 

 published respectively in the years 1773, 1776, and 1779, given descriptions 

 and illustrations of a large number of these numerous types, to all of which 

 he attached distinctive generic and specific titles in conformity with Linnaeus' 

 then newly-introduced binomial system of nomenclature ; each of these 

 compilations, however, possess but minor value compared with the work 

 first quoted. To this latter, one is justified, indeed, in conceding as important 

 a status, as compared with all preceding literature upon the subject, as is sub- 

 sequently commanded by C. G. Ehrenberg's classic volume, ' Die Infusions- 

 thierchen,' published a little over half a century later. As might be anticipated, 

 O. F. Muller embraces in his 'Animalcula Infusoria' numerous minute 

 organisms that find no place in the infusorial group as at present constituted, 

 although in this respect he trespasses but slightly from the path subse- 

 quently pursued by Ehrenberg. In all, Muller institutes seventeen generic 

 denominations, the whole of which are still in use, and only one, his genus 

 Cercaria, being founded upon forms not admitted into Ehrenberg's system 

 of classification, while another, his genus Vibrio, embraces in addition to 

 many common forms of Bacteria, Vibrio, and Spirillum, as now recognized, 

 various examples of the microscopic hair-worms or AngnillulcE. The several 

 species of Stentor were now recognized as members of the same infusorial 

 series, and transferred to his somewhat comprehensive genus, Vorticella. As 

 a necessary consequence of the very imperfect instruments available for 

 investigation at this early date, little more than a rough general outline of 

 the species examined, and no details of their internal organization, are 

 usually recorded, while in many of the types figured the cilia are but repre- 

 sented in part, or even altogether omitted. A reproduction of O. F. Muller's 

 generic subdivisions and earliest proposed scheme of classification of the 

 Infusoria will be found in the chapter hereafter devoted to this special 

 subject. 



In the long interval intervening between the publication of Muller's ' Ani- 

 malcula Infusoria ' and the appearance of Ehrenberg's world-famed treatise, 

 a considerable number of investigators occupied themselves in the study of 

 these m.inute organisms, but without achieving any very notable results. 



