198 ROTIFERA CHAP. 



only figured many species, but gave good short diagnoses of their 

 characters. Ehrenberg in 1838 brought out his magnificent 

 Infusionsthierchen, which contains descriptions and figures of 

 what are now divided into Protophyta, Protozoa, Eotifera, and 

 Gastrotricha. Dujardin's monograph on the " Infusoires," in the 

 Suites a Buffbn? was in several respects an advance on Ehren- 

 berg, whose power of observation was so great as to render his 

 mistakes the more inexplicable. But Ehrenberg ever adhered to 

 his errors as firmly as to his facts. 



The occurrence of Eotifers among microscopic plants induced 

 the botanists Cohn and Williamson 2 to work at their structure ; 

 the group has been studied by men engrossed in other profes- 

 sional cares, such as Gosse, Bedwell, Moxon, Eousselet, and 

 Maupas. Huxley, 3 Leydig, 4 and Cohn 5 studied Rotifers in the 

 '50's and early '60's with a precision the more remarkable when 

 we remember the imperfect methods then available. This period 

 was closed by the valuable monograph published in Arlidge's (4th) 

 edition of Pritchard's Infusoria? under the supervision of W. C. 

 Williamson. Leidy began the study of the American Rotifers. 

 Eckstein 7 gave a careful and interesting account of the species 

 about Giessen in a richly illustrated paper. In recent times the 

 modern methods of histological and embryological research have 

 been applied by Vallentin, 8 Plate, 9 Tessin, 10 and Zelinka, 11 the 

 three Studien ueber Rotatorien of the last author being indispens- 

 able to every student, and containing a full bibliography. 



Hudson and Gosse's Monograph (1886-89) contains a history 

 of the class to which, as to the whole book, we are deeply in- 

 debted ; and a full systematic account of all published species. 

 C. Rousselet has introduced a method 12 of preparation of Rotifers 

 in microscopic slides which enables workers to preserve the types 

 they figure and describe for future identification and comparison. 

 Gunson Thorpe has collected and studied Rotifera in China and 



Paris, 1841. Quart. Journ. Micr. Sci. vol. i. 1853, pp. 3-8, 65-76. 



Trans. Micr. Soc. London, vol. i. (n.s.), 1853, pp. 1-19. 

 Verh. Ges. Wiirzb. vol. iv. 1854 ; Zeitschr. wiss. Zool. vols. iii. vi. 1851-55. 

 Zeitschr. wiss. Zool. vols. vii. ix. xii. 1856-58-63. 



London, 1861. 7 Zeitschr. wiss. Zool. vol. xxxix. 1883. 



Ann. Nat. Hist. ser. 6, vol. v. 1890, p. 1 ; viii. 1891, p. 34. 

 Jen. Zeitschr. Nat. vol. xix. 1886 ; and Zeitschr. wiss. Zool. vols. xliii. xlix. 

 1886-90. 



10 Zeitschr. wiss. Zool. vol. xliv. 1886, p. 273. 



11 Ibid. vol. xliv. p. 396 ; xlvii. 1888, p. 353 ; liii. 1892, p. 1. " See p. 228. 



