CHAPTER VII 

 THE PROTOZOA OF TEE SEA SHOEE 



WE shall now study the principal forms of animal life to be found 

 on the sea shore ; and, in order that the reader may thoroughly 

 understand the broader principles of classification, so as to be able 

 to locate each creature observed in its approximate position in the 

 scale of life, we shall consider each group in its zoological order, 

 commencing with the lowest forms, and noting, as we proceed, 

 the distinguishing characteristics of each division. 



The present chapter will be devoted to the Protozoa the 

 sub -kingdom that includes the simplest of all animal beings. 



Each animal in this division consists of a minute mass of a 

 jelly-like substance called protoplasm, exhibiting little or no 

 differentiation in structure. There is no true body-cavity, no 

 special organs for the performance of distinct functions, and no 

 nervous system. 



Perhaps we can best understand the nature of a protozoon by 

 selecting and examining a typical example : 



Remove a small quantity of the green thread-like algous weed 

 so commonly seen attached to the banks of both fresh and salt 



water pools, or surrounding floating 

 objects, and place it in a glass with 

 a little of the water in which it 

 grew. This weed probably shelters 

 numerous protozoons, among which 

 we are almost sure to find some 

 amoebce if we examine a drop of 

 the water* under the high power of 

 a microscope. 



The amoeba is observed to be a minute mass of protoplasm 

 with an average diameter of about one-hundredth of an inch, 

 endowed with a power of motion and locomotion. Its body is not 



FIG. 50. THE AMCEBA, HIGHLY 

 MAGNIFIED 



