3-23 



/■i, 



Observations on Male Rotifers. 



By W. Wesche, F.R.M.S. 



(^Bead April \Wi, 1902.) 



Plates 17 and 18. 



The males have only been seen in about 20 per cent, of the 

 known species of Rotifers. As they are comparatively so rare, 

 their appearance is always a matter of interest, both from a 

 morphological and a biological point of view. 



It is well kno vn that the large majority of those observed are 

 without digestive organs, but there are two, Proales vjerneckii, 

 and Rhinops vitraea, which are fully equipped with mastax and 

 stomach, and several others with the same organs have been seen, 

 but no drawings or descriptions are yet published. It is probable 

 that the two named will not be as exceptional as was at first 

 thought. 



Members of the Quekett Club may recall with pride that it 

 was at one of our excursions that the first male Rotifer with 

 digestive organs was discovered by Mr. Rousselet. 

 ■ Males are difficult to observe for several reasons. 1. Their 

 size in many cases is very minute. 2. Their movement is very 

 quick. 3. Their appearance is in some cases v^ery dissimilar to 

 that of the female, several being more like infusoria than Rotifers. 



Every collector has his own methods of observation. Personally 

 I fiiid a fiat open trough on the horizontal stage of the microscope 

 the most convenient. This, examined with a power of an inch, 

 enables me to see the smaller animals on a fairly large field, and 

 when I see an organism darting quickly about, I suspect a male 

 Rotifer. Though malas move at a great speed, they usually 



