NUCLEUS OF CHILOMONAS PARAMCECIUM 



EHRENBERG. 



WM. A. KEPNER AND J. G. EDWARDS, 

 UNIVERSITY OF VIRGINIA. 



Chilomonas param<xcium Ehrenberg is perhaps the most com- 

 mon flagellate to be found in laboratory aquaria; but the nature 

 of our paper demands that we describe in detail the species with 

 w T hich we are dealing and our methods of preparation. 



Our specimens were found in dense swarms in laboratory 

 aquaria that had stood for a certain time. The specimens were 

 taken from the aquarium with a pipette and centrifuged. The 

 infusion-water was then decanted off and the animals were next 

 fixed in aceto-sublimate for one to three minutes and then 

 washed and passed into 70 per cent, alcohol and stained in 

 Delafield's hrematoxylin. The stained specimens were mounted 

 in dammar. The length of the fixed animals was as much as 

 thirty microns. In life the posterior end of the animal is some- 

 what pointed and slightly bent dorsally. The anterior end is 

 obliquely truncated from anterior dorsal region posteriorly to 

 ventral side. A pharynx leads from the anterior oblique end 

 of the body well towards or even beyond its middle (Figs. I 

 and 2). Associated with this pharynx are certain small rounded 

 bodies arranged in eight rows, each row lying nearly parallel to 

 the axis of the body. These bodies in life appear as highly re- 

 fractive structures embedded within the wall of the pharynx. 

 Traces of these are not always found in our fixed material. They 

 appear as concentric, arched lines lying parallel to the axis of the 

 body when our fixed material does show them (Fig. 2). Pascher 

 ('13) described these bodies as "kugeligen Kornchen . . . Diese 

 Kornchen entsprechenden der Kornenauskleidung der Furche 

 der niederen Kryptomonaden und rudimentare 'Trichocysten' 

 dar." Belaf ('16) gives a figure of discharged Tapetenkorner or 

 Trickocysten and says: "es scheint hier vielmehr urn mehr oder 



weniger funktionslos gewordene Rudimente der Schleimtricko- 



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