154 



GENERAL BIOLOGY 



Examples : Paramoecium, Coleps, Loxophyllum, Colpoda, Opalina. 

 (Fig. 76.) 



The Holotricha are probably the most primitive Infusoria. Para- 

 moecium caudatum is the best known species. Members of the follow- 

 ing genera are frequently found in fresh-water cultures : Coleps, Lox- 

 ophyllum, and Colpoda. Opalina ranarum is a large multi-nucleate spe- 

 cies living in the intestine of the frog. It has no mouth, but absorbs 



Fig. 75. Sarcocystis 

 miescheriana. 



(Doflein.) 



A, a cyst; B, Pork 

 containing cysts. 

 (From Pratt's "Man- 

 ual" by permission of 

 A. C. McClurg & Co.) 



A. 



B. 



Fig. 76, 



A. Coleps hirtus Ehr. (After Maupas). 



B. Division phase of A. 



C. Opalina ranarum, (After Bronn). 



D. Colpidium colpoda. (Calkins). 



E. Loxophyllum rostratum (Conn.) 



digested foods through the surface. 



31. Order 2. Heterotricha ( ) Ciliata whose 

 cilia cover the entire body, but are larger and stronger about the mouth 

 opening than elsewhere. This adoral ciliated spiral consists of rows of 

 cilia fused into membranelles and leads into the mouth. 



Examples: Spirostomum, Bursaria, and Stentor. (Fig. 77.) 

 Stentor ( ) may be either fixed or free swim- 



ming. It is trumpet-shaped when attached and pear-shaped when swim- 

 ming. The cuticle is striated and just beneath it are muscle fibers 

 (myonemes). The nucleus is ellipsoidal, or like a row of beads. 



32. Order 3. Hypotricha ( ) Ciliata with a 

 flattened body and dorsal and ventral surfaces. The dorsal surface is 

 free from cilia, but spines may be present. The ventral surface is pro- 

 vided with longitudinal rows of cilia and also spines and hooked cirri, 

 which are used as locomotor organs in creeping about. The cilia around 

 the oral groove aid in swimming as well as in food taking. There is a 

 macronucleus, often divided, and two or four micronuclei. 



Examples: Oxytricha, Stylonychia. (Fig. 78.) 



33. Order 4. Peritricha ( ) Ciliata with an 



