PART II 



AMCEBA t UNICELLULAR AND MULTICELLULAR ANIMALS 



FROM your study of the frog you will have learnt 

 some of the more important facts with regard to the 

 morphology and physiology of a comparatively highly- 

 organised animal, and will have overcome a number of 

 preliminary difficulties in acquiring a knowledge of zoo- 

 logical terminology and technique. You will now, 

 therefore, be in a better position to undertake a syste- 

 matic and comparative examination of a number of other 

 animals some much less complicated, some more com- 

 plicated, than the frog working upwards from the 

 simple to the complex forms. In doing so, you must 

 continually bear in mind the deductions in connection 

 with the theory of evolution referred to in the previous 

 chapter. 



Let us begin with a very instructive animalcule 

 belonging to the genus Amoeba. Amoebae are often 

 found in the slime at the bottom of pools of stagnant 

 water, adhering to weeds and other submerged objects. 



They are mostly invisible to the naked eye, rarely 

 exceeding of a millimetre (i^th inch) in diameter, so 

 that it is necessary to examine them entirely by the aid 

 of the microscope. Though they can be seen and 

 recognised with the low power, the high power is neces- 

 sary for the accurate examination of their structure. 



