THE LIFE OF THE SIMPLEST ANIMALS 15 



food of Gregarina is the liquid food of the host as it exists 

 in the intestine, and which is simply absorbed anywhere 

 through the surface of the body of the parasite. There is 

 no mouth opening nor fixed point of ejection of waste 

 material, nor is there any contractile vacuole in the body. 



In the method of multiplication or reproduction Gre- 

 garina shows an interesting difference from Amoeba and 

 Paramwcium and Vorticella. When the Gregarina is 

 ready to multiply, its body, which in most species is rather 

 elongate and flattened, contracts into a ball-shaped mass 

 and becomes encysted that is, becomes inclosed in a tough, 

 membranous coat. This may in turn be covered externally 

 by a jelly-like substance. The nucleus and the protoplasm 

 of the body inside of the coat now divide into many small 

 parts called spores, each spore consisting of a bit of the 

 cytoplasm inclosing a small part of the original nucleus. 

 Later the tough outer wall of the cyst breaks and the 

 spores fall out, each to grow and develop into a new Gre- 

 garina. In some species there are fine ducts or canals 

 leading from the center of the cyst through the wall to the 

 outside, and through these canals the spores issue. Some- 

 times two GregarincB come together before encystation and 

 become inclosed in a common wall, the two thus forming a 

 single cyst. This is a kind of conjugation. In some spe- 

 cies each of the young or new GregarincB coming from the 

 spores immediately divides by fission to form two indi- 

 viduals. 



8. Marine Protozoa. If called upon to name the char- 

 acteristic animals of the ocean, we answer readily with the 

 names of the better-known ocean fishes, like the herring and 

 cod, which we know to live there in enormous numbers ; the 

 seals and sea lions, the whales and porpoises, those fish-like 

 animals which are really more like land animals than like 

 the true fishes ; and the jelly-fishes and corals and star-fishes 

 which abound along the ocean's edge. But in naming only 

 these we should be omitting certain animals which in point 



