THE PROTOZOA. 



pairs and form amoebulse. 

 imperfectly known. 



The life-history is however still 



II. PARAMECIUM AURELIA. 



This is a free-swimming freshwater protozoon found in 

 abundance among decaying vegetable matter. It differs 



n e:p av 



Fig. 9. Paramecium aurelia, seen from above and slightly from the 

 right side : x 300. (c. h. h.) 



AV, anterior pulsating vacuole. EC, ectosarc : the lines running across 

 it indicate the trichocysts. EN, endosarc. EP, micro-nucleus. FV, food- 

 vacuole. M, mouth. MY, 'myophan' striation. N, mega-nucleus. OG,oral 

 groove. PV, posterior pulsating vacuole, in systole. TR, discharged tricho- 

 cyst threads. X, cilia. 



from Amoeba in its more definite shape ; in the more marked 

 differentiation of ectosarc and endosarc ; in the presence of 

 cilia and the absence of pseudopodia ; in its active locomotion 

 by means of cilia ; and in the possession of a definite mouth, 

 and of definite dorsal and ventral surfaces, and anterior and 

 posterior ends. 



Put a drop of water containing Paramecia on a slide in 

 weak melted gelatin to limit the movements of the animals ; 

 cover, and examine with low and high powers. 



A. General Appearance. 



The animal is an elongated, somewhat flattened body 

 about too inch in length, rounded at its narrow anterior end, 

 and bluntly pointed at the broader posterior end. 



It swims actively by means of cilia distributed over its 



