THE SLIPPER ANIMALCULE {Paramecium) 



Paramecium, one of the ciliate Infusoria, is a minute animal found in water 

 in which decaying organic matter is present. It may be seen with the naked 

 eye, A culture of Paramecia can be obtained by steeping hay in water and 

 allowing it to decay, and by adding to this infusion some weeds from a fresh- 

 water pond which contains Paramecia. 



Put a drop of water containing Paramecia on a slide, and place a cover-slip 

 over it. Use a square cover-slip, and put a dot of soft wax on two comers at one 

 side, so as to raise the slip slightly. Examine the slide under the low power. 



Form and General Structure. 



Note that the general form of Paramecium, is definite ; it is roughly oval in 

 outline, being somewhat rounded anteriorly and bluntly pointed posteriorly. 



Micronucleus 



Meganucleus 



Collectiag canal Contractile ^'/■'" 



"• ^ vacuole 



Myophan 

 stria tions 



Trlchocysts 



Contractile vacuole 



Cortex 



Medulla 



Food vacuole 



Mouth 

 CEsophagus 



Fio. 2.— Paramecium caudattm (highly magnified). After Butschli. 



Examine a Paramecium under the high power and note the following 

 structures : — 



(a) The ectoplasm, ectosarc or cortex, which consists of four layers : 



(i) The pellicle, the outermost tough investing layer, which gives 



definite form to the creature, 

 (ii) The contractile layer of myoneme threads or myophan striations, 

 (iii) The trichocyst layer. The trichocysts, minute spindle-shaped 

 bodies, arranged side by side. When the animal is irritated, 

 by adding a drop of very dilute acetic acid, each trichocyst 

 discharges a very fine thread, very much longer than the 

 ciUa ; and the creature is then clothed in a matted coating of 

 fine hairs. The function of these trichocysts is protective. 



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