SCIENCE-GOSSIP. 



33 



NOTES ON ROTIFERA. 

 By Walter Wesche. 



THERE is much literature on the subject of 

 rotifera hidden away in the "Proceedings" of 

 various societies, but the well-known work of Dr. 

 Hudson and Mr. P. H. Gosse is for general inquirers 

 the last word on the subject. The section in the 

 " Cambridge Natural History," beyond giving in a 

 note Mr. Roussellet's discovery of a mastax in the 

 xnale of Proales (JYotovmiata) wernecliii, does not 



shows with comparative ease much that has not 

 before been seen. Mr. Roussellet has also suc- 

 ceeded in inventing a method of preserving and 

 mounting Rotatoria that is very valuable, as it 

 enables types of species to be kept for reference, 

 or pickled specimens to be sent from all parts of 

 the world. 



A well-equipped microscopist can now see a 

 greater amount of structural detail in the smaller 

 rotifers under -^th of an inch in size than is even 

 suggested in the figures drawn in Hudson and 

 Gosse. It must not be forgotten that that work 

 follows in general idea the celebrated folio, "Die 

 Infusionsthierchen," of C. G. Ehrenberg, published 

 at Leipzig in 1838. Though the plates on the 



ii.£l . V 



Fig. 1. Polyarthra plaliptera Ehrenberg. Dorsal view. 

 Drawn from life by W. Wesche. 



.attempt to bring the subject up to date, and is a 

 brief digest of Hudson and Gosse. That work was 

 published in 1889, but the majority of Mr. Gosse's 

 .studies and drawings were made thirty years before 

 that time. It is obvious, however, that when he 

 took up the matter again as collaborator with Dr. 

 Hudson more modern methods of substage illu- 

 mination and modern lenses were not used. 



The difficulty of accurately observing the smaller 

 rotifers, and seeing the very minute detail, is caused 

 by their habitual restlessness. The old type of 

 live box and compressorium kept them fairly quiet, 

 but did not permit any careful substage illumina- 

 tion. The ingenuity of Mr. C. Roussellet, F.R.M.S., 

 has conquered this by the apparatus that bears his 

 name, the use of which, with modern objectives, 



Dig. 2. Nolommata lacinulala Ehrenberg. 

 Drawn from life by W. Wesche. 



a. Lateral view. b. Dar sal view. c. Diagram of trophi, inrsi 

 d. Diagram of trophi, lateral. 



Rhizota and Bdelloida are an advance on those in 

 the earlier work, the figures of others are drawn 

 on the somewhat conventional type given by the 

 Prussian naturalist. 



Both Dr. Hudson and Mr. Gosse considered the 

 family Notommata to be the most interesting 

 group for study. It is in this family that the 



