CHAPTER IV 



OPALINA : MONOCYSTIS PARASITISM BIOGENESIS AND 

 ABIOGENESIS CLASSIFICATION OF THE UNICELLULAR 

 ORGANISM EXAMINED. 



AMONGST the Protozoa (see p. 220) are found certain 

 forms which are parasites. Parasites are organisms 

 which live in association with other organisms, the 

 ready digested food of which they utilise, or even 

 nourish themselves from the tissues of the forms they 

 infest. It will be interesting to compare Paramcecium 

 with a ciliate infusor which lives in the intestine of 

 the common frog, and is known as Opalina ranarum. 



Opalina has a flattened body with an oval outline 

 (Fig. 73, A, B), and full-sized specimens may be as 

 much as i mm. in length. The protoplasm is divided 

 into cortex and medulla, and is covered with a cuticle ; 

 the cilia are equal-sized and uniformly arranged in 

 longitudinal rows over the whole surface. 



On a first examination no nucleus is apparent, but 

 after staining, a large number of globular nuclei can be 

 seen (B, nu) : these nuclei multiply within the body 

 of the infusor. 



The presence of numerous nuclei in Opalina is a fact 

 worthy of special notice. The unicellular organisms we 



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