88 PROFESSOR O. BUTSCHLI. 



Astasia trichophora, Claparede {' Etudes sur les Infusoires,' 

 pp. 41—346). 



Astasia trichophora^ Clark {' Ann. and Mag. Nat. Hist.,' 

 4th ser., vol. i, p. 250, pi. vi, fig. 45). 



These organisms appear undoubtedly to possess a mouth; 

 Pi. vi, fig. 18, a, represents a specimen which measures across 

 the centre 0"05 mm. The form is very variable, ovping to 

 the capability of energetic contraction possessed by the body; 

 apparently due to the partial contraction of the outer layer. 

 These layers are usually arranged in rings round the body, 

 so that in individual zones there is at one line an increase, 

 and at another a decrease in size, and in consequence the 

 whole either elongates or contracts. The greatest amount 

 of contraction causes the body to assume an almost spherical 

 shape. In large specimens the author has observed a fine and 

 delicate spiral striping of the outer layer of the body surface, 

 resembling the condition seen in Eugle7ia viridis. The anterior 

 end of the body which carries the flagellum, is generally some- 

 what narrowed, and is sharply truncate ; the animal moves 

 slowly, with a sliding and tolerably constant motion. The 

 flagellum is considerably larger than the body when extended 

 to the full ; it is carried quite straight and fixed, and the 

 extremity alone performs vibrating movements. Specimens 

 with no flagella are occasionally met with ; in such cases 

 movement is effected as in Euglense with no flagella, by 

 the contractility of the body; such organisms are probably 

 in the act of becoming encysted. The posterior end is gene- 

 rally rounded and is never pointed, as described by Clark. 

 The author is also unable to verify Clark's description of an 

 eyespot. 



The mouth apparatus, of which it is not easy to give an 

 account, is situated at a short distance behind the base of 

 the flagellum. A thick dark band is seen upon one of the 

 flat surfaces of the body, not far from the base of the flagel- 

 lum (fig. 18, a), which can be traced backwards for a 

 longer or shorter space, becoming gradually narrower, 

 till it ultimately disappears. This band has been seen to 

 consist of two lines, lying so close to each other as to appear 

 as a nearly closed tube when seen in optical section. At 

 the front end of the band a transparent circle is often seen, 

 together with one or two delicate streaks which run off to 

 the base of the flagellum (fig. 18, a). The posterior 

 double stripe will, upon this hypothesis, be the walls of 

 what is usually a closed oesophagus, which arises from a 

 chink-like cytostome situated between the anterior end of 

 this band and the base of the flagellum. The mode in which 



