II] CILIATA 35 



protoplasmic funnel projecting from one end called the collar, from 

 the centre of which a flagellum protrudes. To the collar adhere 

 particles of food swept in by the spiral motion of the flagellum 

 and in its substance they are engulfed. Ordinary Flagellata like 

 Euglena are termed Lissoflagellata. The members of this group 

 which live in the blood of animals are often termed Haemato- 

 flagellata although this is not a scientific ground of division. 

 Of these the most dreaded is Trypanosoma, characterised by having 

 a flagellum bent back at its point of origin and attached to the 

 border of the animal forming the so-called undulating membrane, 

 whilst a free portion projects behind. The nucleus is divided into 

 two, one portion remaining in the centre of the animal whilst another 

 portion, the kineto-nucleus, lies just beneath the flagellum. This 

 animal lives in the blood of vertebrates in .one stage of its existence 

 and one species causes in Man sleeping sickness a disease which is 

 a low fever in its early stages and in its later a disease of the brain. 

 The parasite is conveyed from one person to another by a fly 

 (Glossina palpalis) which sucks the blood of the- person infected and 

 in this way receives the parasite into its own interior where it 

 undergoes rapid division. The resulting germs are then injected 

 by the fly along with its saliva into the blood of another victim. 

 The next group of Protozoa which we shall describe are termed 

 the Ciliata. As the name implies their locomotor 



Ciliata. . , . , . , ., , ., , . 



organs are numerous cilia which are vibratile hairs 

 like flagella but much shorter and having a simple oar-like motion 

 of a simpler character than the whip-like motion of flagella. The 

 Ciliata differ from all other Protozoa in having two kinds of nuclei, 

 one sort of which only comes into use when the conjugating gametes 

 are formed. If we examine the roots of Duckweed with a lens, we 

 shall probably find some coated with a whitish scum ; if these be 

 cut off and mounted in a drop of water on a slide and examined 

 with a low power, they will be seen to be covered by numerous 

 specimens of a most beautiful animal called Vorticella. Vorticella 

 has something the shape of a blue-bell flower ; it consists of a long 

 delicate stalk and a bell-shaped body ; by means of the stalk it is 

 fixed to some definite support, such as, for instance, the Duckweed 

 root. . The part of the body corresponding to the lip of the bell is 

 broad and turned outwards ; encircled by this lip, which is called 

 the peristome, there is a flattened projection called the disc. 

 Between the peristome and disc there is a peristomial groove, and 

 in this we can make out some short hair-like structures waving to 



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