FLAGELLATE INFUSORIA AND ALLIED ORGANISMS. 79 



long flagellum of even thickness throughout; it generally 

 moves along its whole length with a serpentine, less fre- 

 quently with a rolling, motion. The author has noticed a 

 small accessory flagellum close to the flagellum known to 

 Ehrenberg. The accessory flagellum is generally at rest in 

 an extended condition. Biitschli also believes that he 

 has seen a delicate thread arising from the posterior end of 

 the body, and attaching it to the base of the case. The eye- 

 spot lies close to the base of the flagellum, whilst the two 

 contractile vacuoles are close to each other at the hinder 

 portion of the anterior third of the body ; the contraction of 

 these vacuoles is quick and sudden. Focke^ was the first to 

 recognise a single contractile vacuole in these organisms, 

 and after him Claparede described and figured them. No 

 nucleus was observed by Biitschli, as the little free-swimming 

 colonies are difficult to treat with reagents. Occasionally a 

 group of small granules of high refractive index were ob- 

 served in the hinder third of the body ; it cannot be decided 

 whether the minute organisms take solid food. Fromentel 

 has lately described a dark cytostome at the base of the 

 flagellum ; he appears to have mistaken the eyespot in this 

 way. 



As regards the formation of a colony, the following points 

 are noticed by Biitschli : — The colony is doubtless formed by 

 fission of the organisms in their cases, but the actual fission 

 has not yet been followed out. Calices have, however, been 

 seen, which, in addition to an individual situated at the 

 bottom, have a second caseless form placed at the month of the 

 calyx (fig. 13 b). It appears to be proved that these two 

 individuals have proceeded from the fission of the previous 

 inhabitant of the calyx, since each contains only a single 

 pigmented disc, whilst the anterior one alone possesses an 

 eyespot. Carter has observed a somewhat similar phenomena 

 in the fission of his Euglena agilis in its encysted state, for the 

 hinder product of division is in the same way devoid of an 

 eyespot. The anterior organism, in a more advanced stage, 

 is attached to the mouth of the calyx by its posterior pointed 

 extremity, and then a small calyx forms round its hinder 

 half. 



A large cyst (fig. 13, a, c) has been seen at the mouth 

 of an empty calyx ; it consisted most exteriorly of a coarse 

 sheath containing a smaller excentric sheath ; this in turn 

 was filled with a protoplasmic contents and the two charac- 

 teristic pigment discs. No eyespot was visible, but the 



1 ' Pbysiologische Studien,' Hft. 2. 



