14 GUIDE TO THE CORAL GALLERY. 



High Wall EucecrijplwJus sdiultzei has only two segments, the lower being 



£^®® , , expanded out, and the central capsule is lobed ; see Model IG in Case. 

 Gallery. IV. Phaeodaria (Models 17, 18), with a double-walled central 



capsule with a few large orifices, and surrounded by dark brown 

 pigment. The skeleton of Auhsphcera (Model 17) is formed entirely 

 of tubes of silex, which join to form a spherical lattice with triangular 

 meshes, a tube with verticils of spines radiating from each node. 

 This species, which lives at the surface in the Mediterranean, has a 

 large shell ^^ of an inch in diameter. 



Aulacantha (Model 18) has a skeleton formed of hollow siliceous 

 tubes of two kinds, viz., radiating spines and loose needles arranged 

 tangentially on the surface. 



CORTICATA OR INFUSORIA. 



If any animal or vegetable substance be allowed to remain in a 

 vessel of clear water exposed to the air, in a short time tiny specks 

 will be seen swimming about. The organisms appearing in these 

 infusions were termed Infusoria or Infusions Animalcules. The 

 organic matter has simply served as nutriment to the germs of 

 these Animalcules previously existing in the water or in the air. 

 Infusoria abound in fresh and stagnant water and also in the sea. 



The organisms grouped under this name differ from the Gymno- 

 myxa, in having, in their adult phase, a dense cortical body-layer and 

 often flagella or cilia in place of pseudopods. A cilium is a hair-like 

 organ which can only bend and straighten itself, and which only 

 acts in unison with other cilia. A flagellum acts independently, and 

 with a lashing to and fro movement. 



The Corticata may be roughly divided into four groups : Sporo- 

 zoa, Flagellata, Ciliata, and Acinetaria. 



Sporozoa. 



The Sporozoa are parasitic Protozoa which live in the tissue-cells 

 and fluids of other animals. The study of these organisms has of late 

 years acquired an immense importance on account of the wide-spread 

 and dangerous maladies to which some of them give rise in man, 

 domestic animals, fishes, &c. For instance— to mention a few of the 

 more important diseases — the various kinds of malaria in man, Texas 

 fever in cattle, coccidiosis in rabbits and other animals, " psorosperm " 

 disease (myxosporidiosis) in fishes, silkworm disease, and sarcospori- 

 diosis in cattle, are all due to the presence of Sporozoa in the blood 



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