CHAPTER I. 



^ FIRST BRANCH OF ANIMALS. 

 PROTOZOANS (First Animals). 



General Characteristics. The Protozoans are one-celled 

 animals, in this differing from all others. The lowest 

 forms resemble microscopic bits of the white of an egg. 

 They have no definite shape, and move by a bulging out 

 of the body-mass into root-like projections called pseu- 

 dopodia, or false feet. In the interior are minute granules 

 that move about (circulate), and in all, except the lowest 

 protozoans, is seen a central oval body called the nucleus, 

 and a hollow, transparent space, that contracts and en- 

 larges with some regularity, called the "contractile vesi- 

 cle." The higher forms have silicious or calcareous shells 

 and permanent organs. 



Class I. MONERS. 



These are shapeless bits of transparent matter (Fig. i) 

 containing merely circulating granules. By extending the 

 body into pseudopodia, or false feet, and contracting them, 

 they glide slowly along. Their prey is seized by sur- 

 rounding it with the false feet, which fuse about it, and 

 the victim is absorbed into the body-mass. They repro- 

 duce by simple division, or as in Fig. i. The Moner as- 

 sumes a thick covering (becomes encysted), #, divides into 

 spheres, , that burst out, c, d, e, and soon assume the 

 parent form, / 



