FLAGELLATE INFUSORIA AND ALLIED ORGANISMS. 81 



discover the mouth lying terminally, according to Diesing's^ 

 statement. Very interesting are the active movements of the 

 protoplasm to be observed in the organism at rest. These cir 

 cular streamings, which are recognised by the rapid displace- 

 ments of the very numerous vacuoles and the contained par- 

 ticles, occur regularly, but with a motion which is sometimes 

 slower, and sometimes more rapid, whilst often the direction of 

 the stream is entirely changed. The relation of the contractile 

 vacuole is also interesting (fig. 14, c). Here and there in the 

 protoplasm vacuoles are seen to circulate, such vacuoles, re- 

 markable for their size, being pushed towards the screw-like 

 posterior end ; after some time they contract. This condition 

 of the vacuole calls to mind a similar one in various Amoebae, 

 e.g. Amosba guttula, Duj., Umax, Auerb., and others, in 

 which the vacuole, after being formed in the protoplasm of 

 the body, has been seen to contract at the posterior extremity 

 of the moving animal. The nucleus is best seen either in a 

 dying organism or in one lately dead, as a rounded, pale 

 body, of considerable size, in which, sometimes but not 

 always, a small clear area is visible. Its position is constant 

 at the anterior extremity of the body (fig. 14, c.) and fre- 

 quently, instead of one such nucleus, two are found lying close 

 together. Reproduction is by transverse fission, according 

 to Perty, but the author is doubtful on this point. 



Hexamitus, Dujardin (' Histoire nat. des Infusoires,' 

 Paris, 1841, p. 296, pi. iii, fig. 16). 



Hexamitus inflatus, Dujardin (op. cit., p. 296). 



Dujardin has described three forms of this characteristic 

 genus, which he has called Hexamita, from the sex- 

 tuple arrangement of the flagella. Of these forms two, Hex- 

 amita nodulosa and injlata, are found in foul marsh water, 

 whilst the third, Hexamita ititestinalis , is parasitic in the in- 

 testine and body cavity of the frog and newt. Butschli is 

 inclined to believe that these are only two varieties, differing 

 somewhat, of a single species, which are most nearly related 

 to the form injlata, and he has consequently chosen this 

 name for both the forms. The Flagellata in question were only 

 once found, and that in foul marsh water ; they are not 

 very common. Their appearance is somewhat variable ; they 

 occurred at first in the extended form (fig. 15, a), but at a 

 later period, and much oftener, they were found as short, 

 rounded organisms (fig. 15, b). This shape appears to change 

 very easily, since such a form as fig. 15, b, lying at rest, has 



' " Revision der Prothelminthen," ' Sitzungsber, d. k. Acad, zu Wien,' 

 1865, Bd. Iii, p. 323. 



VOL. XIX.-»— NEW SEE, F 



