ZOOLOGY 



Order 5.— Sarcocystidea. 



The best known form of this order is Sarcocystis (Fig. 68), which occurs in 

 flesh of mammals, each parasite having the form of a, long spindle embedded 



68. -Sarcocystis miescheri, adult form (s) in striped muscle of pig. (From 



Butschli's Protozoa, after Rainey.) 



a striped muscular fibre. They are often known as Rainey's or Miescher's 

 •puscles. The protoplasm divides into spores from which falciform young are 

 erated. 



CLASS v.— INFUSORIA. 



1. Example of the Class — Paramoecium caudatum. 



Structure. ^Faram(Ecm7]i; the "slipper- animalcule," is tolerably 

 mmon in stagnant ponds, organic infusions, &c. The body 

 'ig. 69) is somewhat cylindrical, about |- mm. in length, rounded 

 the anterior and bluntly pointed at the posterior, end. On the 

 ntral face is a large oblique depression, the buccal groove (hue. gr.), 

 iding into a short gullet (guL), which, as in Euglena, ends in the 

 ft internal protoplasm. 



The body is covered with small cilia arranged in longitudinal 

 ws and continued down the gullet. The protoplasm is very 

 sarly differentiated into a comparatively dense cortex (cort.) and 

 semi-fluid medulla (med.), and is covered externally hy a thin 

 lliclc or cuticle (cu.) which is continued down the gullet. The 

 lia are continuous with the pellicle. 



In the cortex are found two nuclei, the relations of which are 

 ;ry characteristic. One, distinguished as the meganucleus {nu.), 

 a large ovoid body staining evenly with aniline dyes, which, 

 [len it divides, does so directly by a simple process of constriction. 

 tie other, called the micronucleus (pa. nu.), is a very small body 

 Dsely applied to the meganucleus; when it divides it goes 

 rough the complex series of stages characteristic of mitosis 



The contractile vacuoles {c. vac.) are two in number, and are very 

 adily made out. Each is connected with a series of radiating 

 dndle-shaped cavities in the protoplasm which serve as feeders 



it. After the contraction of the vacuole these cavities are seen 

 ■adually to fill, apparently receiving water from the surrounding 



