420 MR. P. H. GOSSE ON THE STRUCTURE, FUNCTIONS, AND HOMOLOGIES 
BERG took them up. He penetrated into the minute org-anization of these animals ; 
resoh^ed and figured, with a precision and minuteness up to that time unattempted, 
the nutritive, circulatory, nervous, muscular and generative systems ; and, though the 
details of some of the organs which he has described existed only in his imagination, 
and the functions of others which he clearly saw were quite misunderstood, it would 
be absurd to deny that his elaborate plates and descriptions are generally faithful 
representations of these minute creatures. 
4. M. Dujardin, like his great predecessor, included the Rotifera, by the name of 
SystoUdes, among the Infusoria, in his work on the subject published in 1841. In 
many particulars his observations, which were largely polemical, have advanced our 
knowledge of the subject ; but in some respects they are a retrogression. His per- 
sonal acquaintance with species was greatly inferior to that of the Prussian zoologist, 
and insufficient for satisfactory generalisation. 
5. Since then, I am not aware that any naturalist has attempted, from personal 
observation, a revision of the class, or even of any considerable number of species; 
and the science has advanced, chiefly, by isolated papers on individual species, and 
by critical examinations of the facts already accumulated. These memoirs I shall 
enumerate in chronological order. 
6. In 1843, Dr. Kolliker published a memoir* on Megalotrocha, confining him- 
self to the segmentation of the egg, and the (so-called) seminal threads. Dr. Oskar 
Schmidt, in 1846, gave a resume of what was then known of the organization of the 
Rotifera generally'!'. same year, the late Dr. Mantell, in his ‘Thoughts on 
Animalcules,’ though chiefly founded on Ehrenberg, added some information of 
interest and value on the development of the young in Stephanoceros and Melicerta. 
In the ‘Annals of Natural History’ for 1848, Dr. Dobie described with minuteness 
two new species of Floscularia and Mr. Brightwell recorded his important disco- 
very of the dioecious character of a Rotiferon which I have since named Asplanehna. 
The same species formed the subject of a valuable memoir by Mr. Dalrymple read 
before the Royal Society in February 1849. Meanwhile, however, some additional 
observations had appeared by Dr. Leydig^, on the egg-segmentation of Notommata, 
EucJilanis, and Megalotrocha •, and in the same year (1848), Dr. Frey had published 
a work on the class generally 1|, which I have not been able to see. 
In 1850 I published several memoirs on Rotifera in the ‘Transactions of the 
Microscopical Society’ and the ‘ Annals of Natural Flistory,’ viz. “ On the Habits of 
Melicerta ringens^" (January); “On the Anatomy of Notommata aurita^"' (May); 
“ On Asplanehna priodonta**" (July); and “ On Notommata parasita^'’’ (December). 
* Froriep’s Neue Not., No. 28. p. 17. f Wiegmann’s Archiv, 1846, p. 68. 
X Philosophical Transactions, 1849. § Isis, 1848, p. 170. 
11 Ueber die Bedeckungen der wirbellosen Thiere. Gottingen, 1848. This work I know only by a citation 
in SiEBonn and Stannius’ ‘ Comparative Anatomy.' 
^ Trans. Micr. Soc. i, pp. 58, 93, 143. 
** Ann. Nat. Hist. July 1850. 
