 Flagellum first discovered by Englemann(1887)  Jansen (1887):- report structure of flagellum of sperm.  Hodge (1950):- detailed ultra structure of flagellum of spermatozoa  Manton :-gave ultra-structure of cilia

 Cilia and flagella are microscopic, hair or thread like motile structures present extra- cellularly but originate intra-cellularly from the basal body and help in movements, locomotion, feeding, circulation etc.

 Central tubules are formed of dynein protein.  Peripheral microtubules formed of tubulin protein  Interdoublet linkers formed of nexin protein.  Quantitatively it is formed of:- 1. Proteins =74-84% 2. Lipids=13-23% 3. Carbohydrates=1-6% 4. Nucleotides= %

 Arise from basal bodies.  Similar in ultra structure.  Similar chemical composition.  Similar in basic function.

Cilia  More in number (14,000/ cell).  Small size(5-10 micro meter).  Distributed on whole body  Beat in either metachronous or synchronous coordination.  Sweeping or rowing motion.  Locomotion, feeding, circulation etc are its function. Flagella  Less in number(1-8), but many in Trichonympha.  Large size(150 micro meter).  Located at anterior end of body.  Beat independently.  Undulatory motion.  Only locomotion.

 Locomotion  Cilia of Paramecium and flagella of collar cells of sponges maintain nutritive-cum-respiratory water current.  Cilia of wind pipe expel out any dust or food particle.  Cilia of kidney-nephrons move nephric filtrate.  Help in conjugation in Paramecium  Flagella circulates the food in coelenterons.  Cilia of larval forms help in their dispersal.

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