LESSONS 



IN 



ELEMENTARY BIOLOGY 



LESSON I 



AMCEBA 



IT is hardly possible to make a better beginning of the 

 systematic study of Biology than by a detailed examination 

 of a microscopic animalcule often found adhering to weeds 

 and other submerged objects in stagnant water, and known 

 to naturalists as Amceba. 



Amoebae are mostly invisible to the naked eye, rarely 

 exceeding one-fourth of a millimetre ( T ^-g- inch) in dia- 

 meter, so that it is necessary to examine them entirely by 

 the aid of the microscope. They can be seen and re- 

 cognized under the low power of an ordinary student's 

 microscope which magnifies from twenty-five to fifty dia- 

 meters ; but for accurate examination it is necessary to 

 employ a far higher power, one in fact which magnifies 

 about 300 diameters. 



Seen under this power, an Amoeba appears like a little 



