PHYLUM PROTOZOA 



53 



Order 2. Sarcosporidia. — Neosporidia usually parasitic in 

 the muscles of vertebrates. Example: Sarcocystis. 



The most common Sarcosporidia are Sarcocystis miescheri- 

 ana in the muscle of the pig, 5. muris in that of the mouse, S. 

 lindemanni, rarely occurring in the muscles of human beings. 



4. Class IV. Infusoria 



a. Paramecium caudatum 



Paramecia are unicellu- 

 lar animals visible to the 

 naked eye if a proper back- 

 ground is provided. They 

 are found in fresh water, 

 and usually appear in cul- 

 tures prepared for Ameba 

 as described on page 28. 



Anatomy. — Paramecium 

 (Fig. 33) is a cigar-shaped 

 animal with a depression 

 called the oral groove (o.g.) 

 extending from the forward 

 end obliquely backward, 

 ending just posterior to 

 the middle of the body. 

 T he mouth (m.) is situate ii- 

 near the end of the oral 



groove. ~~~Endosarc (en.) 

 and ectosarc (ec.) occur in 

 Paramecium as in Ameba. 

 Covering the surface is an 

 additional membrane, the 

 pellicle (p.) or cuticle; this 

 can easily be seen if a 

 drop or two of 35 per cent 



Fig. 33. — Paramecium viewed from the 

 oral surface. L, left side. R, right side. 

 an, anus; ec, ectosarc; en, endosarc; f.v, food 

 vacuoles; g, gullet; m, mouth; ma, macro- 

 nucleus; mi, micronucleus; o. g, oral groove; 

 p, pellicle; tr, trichocyst layer. The arrows 

 show the direction of movement of the food 

 vacuoles. (From Jennings.) 



