192 4 



über die wahre Beschaffenheit ihrer männlichen Geschlechtswerkzeuge erzielen lassen, 

 so dass es noch zweifelhaft ist, ob die Rotatorien Hermaphroditen sind oder getrennte 

 Geschlechter besitzen." — 



It was Brightwell who in 1848 was the first to find a male of the Rotifera 

 and regard it as such. In 1849 it was more thoroughly described by Dalrymple. 

 It was the male of Asplanchna Brightwelli. In 1850 Gosse (p. 18) described the male 

 of A. priodonta. In 1851 Weisse (p. 347) described the male of D/g/e/ïa catellina, but 

 did not regard it as such, describing it as a new species, D. granularis. In 1854 a 

 Leydig (p. 99) supposed that the above named two species, Enteroplea hgdafina and 

 Xotommata granularis, and further the D. granulans of Weisse were really all males 

 of Rotifers: he gave exhaustive reasons for his suppositions, but was not able to 

 prove them; he however described the male of Asplanchna Sieboldi simultaneously. 

 In 1856 CoHX found the male of Hydaäna senia and showed that Leydig's suppo- 

 sition was correct and that the Enteroplea hydatina of Ehrenberg was really the 

 male of Hydatina senta. In 1857 Leydig (p. 404) himself found the Hydatina male 

 and gave valuable contributions to the anatomy of this animal. Already in 1858 

 Gosse's paper: On the Dioecious Character of the Rotifera appeared. In this paper 

 10 Rotifer males were described: of these the seven were really the males of Bra- 

 chionus, the others belonging to Polyarthra platyptera, Sacculus viridis, and Synchœta 

 tremulaÇ?). 



With this paper the common, dioecious character of the whole group was really 

 demonstrated; curiously enough, during the following forty years only very few males 

 were observed; and if they w"ere observed, they were almost always insufficiently 

 described and very badly drawn. Even the large work of Hudson Gosse, with regard 

 to the structure of the males, was hardly of anj' significance at all. From these forty 

 years there exists only a good description and drawing of Euchlanis dilatata (Cohn 

 1858) and of Copeus pachyuras (Dixon-Xlttall 1894). Further, Plate has (1886 a) 

 contributed to the study of the males of Brachionas, Hertwigia, Polyarthra, Triarthra 

 and Asplanchnopus. Hudson-Gosse (1886) described the exterior of the male of Pe- 

 dalion; of the other males mentioned in the work the drawings and descriptions 

 are very insufficient. From this period several papers relating to the structure of the 

 males certainly appear (Metschxikoff 1866: Apsilus; Daday 1883, 1891: Asplanchna; 

 Milne 1885: Diglena; Western 1888: Asplanchnopus; Gastropus clauulatus; 1892 Tri- 

 phylus lacustris; Asplanchna 1890; Thorpe 1889: Megalotrocha; Andersson 1889: 3/e- 

 galotrocha; Rousselet 1892 b Conochilus, 1894 Cgrtosia; Dixox-Nüttall: Stephanoceros 

 1896). But almost all these males are very insufficiently drawn; generally the authors 

 confess that they have only seen a single male and that it died before further ob- 

 servations could be made. 



In the time from 1896 — 1908 a series of very valuable papers appears and 

 our knowledge of the structure of the males is much augmented. Rothert (1896) 

 and Rousselet (1897 d) study the males of Proales Wernecki. Weber (1897 — 1898) 

 gives a series of excellent drawings of males several of which have never been found 



