94 DAVENPORT ACADEMY OF SCIENCES. 



StenTor c^ruleus Ehr. 



Body of a very large size, more or less densely blue in color. 

 Nucleus conspicuous, moniliform. 



lycngth of the extended body, 250-300 microns. (Fig. 153, 

 PI. XXI.) 



In mass this species is one of the largest of fresh water Pro- 

 tozoa, being readily visible to the unaided eye, and of ten gathered 

 in great social clusters. 



Reproduction commonly takes place by oblique division of the 

 body, the first indications of fission being the appearance on the 

 ventral surface of an elongated vibratile membrane which soon 

 breaks transversely into a fringe of long cilia. The anterior 

 extremity of this fringe curls around, meeting the lower end and 

 forming the peristomal cilia for the new individual. Separation 

 of the body then occurs, in an oblique direction. This method is 

 the usual one for all members of the genus and is illustrated by 

 Figs. 154-156, PI. XXI, which probably is another species. 



Reproduction in Stentor ccsrulciis may also take place by the 

 production of internal embryos. Probably originating from the 

 bead-like elements of the nucleus, the embryos assume the essen- 

 tial characters of the adult within the endoplasm of the parent, 

 and finally break out through the cuticular surface. This 

 method of reproduction has been reported to occur in other species 

 of the genus but has come under my observation only in Stentor 

 ceeruleus. The nucleus is usually visible without the aid of re- 

 agents, distinctly moniliform, and sometimes may be branched. 

 The contractile vesicle is spherical, often with a conspicuous canal 

 leading posteriorly. 



A common form, widely distributed, found in old infusions of 

 fresh water after fermentation has taken place. 



Stentor rceselii (?) Ehr. 



Body transparent, greatly elongated when fully extended, 

 sometimes secreting a mucilaginous sheath. Long, slender setae 

 often extended from the periphery. A tuft of short, fine setae 

 developed from the posterior extremity. Nucleus elongated, 

 band-like. 



Eength, when extended, 500-1000 microns. (Figs. 154-156, 

 PI. XXI.) 



