PART II 



CHAPTER I 



AMC.KBA 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 zoological terminology and 

 technique. You will now, therefore, be in a better position 

 to undertake a systematic and comparative examination of 

 a number of other animals some much less complicated, 

 some more complicated, 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 |th of a millimetre ( T ^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 

 necessary for the accurate examination of their structure. 



