PAULINELLA CHROMATOPHORA. 129 



found in the sediment upon dead leaves in company with many 

 Mallomonas Plosslii Perty, some Amoeba radiosa, and Acantho- 

 cystis sp. and an occasional desmid. 



The shells in our specimens were somewhat thicker than 

 Lauterborn describes. 



The bulk of the protoplasmic body varies, but it never fills 

 completely the shell cavity. In one individual the protoplasmic 

 body was contracted into a sharply defined spherical mass, which 

 lay at the base of the shell cavity. Before pseudopodia appear 

 a rounded neck of protoplasm is extended through the narrow 

 neck of the shell. And then suddenly one or more pseudopodia 

 are thrust out from this protruding bit of 

 protoplasm. For a moment the pseudo-. 

 podia remain quiescent ; but they are usually 

 oscillating or slowly waving like a flagel- 

 lum. It is strikingly interesting to see these 

 pseudopodia function as primitive flagella. 



An isolated individual kept in a moist 

 chamber at living-room temperature from 

 January 5 to January 18 showed on the 

 latter date two large horse-shoe sJiapcd chro- 

 matophores which lay side by side with their 

 ends directed towards the mouth of the 

 shell. On January 5 this individual had but 

 one horse-shoe shaped chromatophore. The specimen lived in 

 this condition one week longer when it was accidentally killed. 

 It remains to be seen, therefore, whether these two large chro- 

 matophores were developed as an effect of the artificial environ- 

 ment, or whether they were a step preparatory to cell-division, or 

 a mere variation which will be more frequently met with when 

 greater numbers are found. 



We have not counted the individuals found. They are plenti- 

 ful and can be found with comparative ease in water from the 

 spring-pool by Preston Heights, Charlottesville, Virginia. We 

 have succeeded in keeping Panlinclla chromatophora alive in 

 small aquaria and moist chambers at living-room temperature for 

 periods as long as three weeks. 



UNIVERSITY OF VIRGINIA, 

 February 1 1, 1905. 



