liEPHESENTATl\ ES OF AS I MM. I'llYLA til 



actions constitute the organism and as such it is to be regarded :is 

 superior to its structural components which it builds for itself. 



The laboratory studies throughout the ronuiiiider of the course 

 will be concerned with representative types of each of the animal 

 phyla. This is an attempt to decipher through the study of 

 living animals those features of organization which have endowed 

 animals with such advantages as have enal)led them to advance 

 beyond a given rank. It is also a means of plotting the probable 

 pathway in the descent of animal groups. 



The animals thus studied will l)e arranged in a series in which 

 the succession is from the lower to the higher. 



Review the various grades of groups by means of which ani- 

 mals are classified. 



PHYLUM PROTOZOA 



Class Sarcodina {Amoeba proteus). — The amccba is an organism 

 which affords an opportunity for studying living protoplasm in a 

 relatively simple state, since it exists as a small naked mass of 

 this living substance. 



Place a few drops of the culture containing anui'bir on a slide, 

 cover with a thin cover slip, and allow it to stand for a few 

 minutes until some of the animals have emerged from the 

 detritus of the preparation. Cut down the light and look for 

 specimens using the loiv-power objective of the compound micro- 

 scope. When an irregularly shaped, granular, slow-moving 

 object has been located ask the instructor if the desired animal has 

 been found. These animals appear iron-gray in contrast with the 

 yellowish-brown color of the plant tissues in the culture. Select 

 an active specimen in a clear field and study to determine the 

 mode of locomotion. 



Observe that the outhne of the animal is irregular and variable 

 due to the extension of projections, called pseudopodia, which 

 are constantly changing in position, numl)er, size, and form. By 

 flowing into these projections the animal moves with the type 

 of movement known as amahoid. The pseudopodia are termed 

 "organs of locomotion," since it is through these that movement 

 from place to place is efTected. Notice the outer, thin, dear, 

 firmer layer of protoplasm, called ectoplasm, free from granules, 

 and an inner granular, more \'n\uU\ mass, the ciidoplasm. Do 

 form and locomotion indicate that there are anterior and posterior 

 ends in the animal? 



