FLAGELLATE INFUSORIA AND ALLIED ORGANISMS. 89 



food is ingested gives strength to this theory, for Astasia tri- 

 chophoi'a has been seen to swallow large spherical bodies 

 (fig. 18, b) of unknown nature. The portion of the body 

 close behind the base of the flagellum, where the slit-like 

 cytostome is situated becomes funnel-shaped, and surrounds 

 the food to be ingested. In this funnel is seen a transparent 

 tube of considerable size, whose walls appear in optical sec- 

 tion as delicate bands ; this tube leads backwards, and is 

 the CBSophagus distended for the reception of food ; along it 

 the food materials pass, without any assistance from the 

 flagellum, into the interior of the body. Stein has observed 

 the expulsion of food remains from the posterior end of the 

 body. The contractile vacuole is at the anterior end close 

 to the oesophagus. The contraction is rapid and very sudden, 

 according to Clark. After the contraction several small 

 vacuoles appear, which coalesce to form the new vacuole. 

 In one specimen an elongated space filled with fluid made 

 its appearance, after the contraction of- the vacuole, near one 

 or two small vacuoles in the position of the old one ; the 

 small vacuoles which ultimately coalesced appeared to fuse 

 with this space. The large vesicular nucleus, with dark 

 inner bodies, lies near or somewhat behind the middle of 

 the organism. Within the protoplasm of the body is seen the 

 food, which is not enclosed in vacuoles. Peculiar reddish- 

 brown bodies are also present, as also brownish or brownish- 

 green granules of secretion. These granules are either scat- 

 tered throughout the protoplasm, or they are collected chiefly 

 in the posterior portion of the body. They closely resemble 

 in their very characteristic appearance the secreted granules 

 met with in the Ciliata and in Amoebae, and are remarkable 

 for their peculiar brownish-green, olive-like pigment, and in 

 AmoebsB for their clearly crystalline form. The form of the 

 crystals, as well as their reactions, show that oxalate of lime 

 is present. 



Anisonema, Dujardin (* Hist. Nat. des Infusoires,' 

 p. 344). 



Bodo, Ehrenberg (' Die infusionsthiere als vollkommene 

 organismen,' Leipzig, 1868, p. 34). 



Heteromita, Dujardin (op. cit., p. 297). 



(?) Heteronema, Dujardin (op. cit., p. 370). 



These organisms possess two flagella, situated at the an- 

 terior extremity, which are sharply differentiated from each 

 other by their different conduct in motion. The shorter fla- 

 gellum, which springs from the anterior wall in advance of 

 the other, is the one by the vibrations of which alone the 



