188 



ZOOLOGY 



some of these show a distinct approach to the bacteria 

 or other lowly organized plants. One of the commonest 



A c.V B 



Drawing by R. Weber, after Lcidy 



FIG. 36. A , Amiba diffluens. B, Amiba radiosa. Greatly magnified, n, nucleus ; 

 c.v., contractile vacuole; p.p., pseudopodia. The contractile vacuoles are excretory 

 organs. They become filled with waste fluids and gases, which they eventually pour 

 out on the surface of the body, contracting as they do so. Thus they possess, in a 

 very simple form, functions of the lungs and kidneys of higher animals. They differ 

 in function from the lungs in not being connected with the absorption of oxygen, 

 which is taken in through the surface of the body. 



flagellates in ponds and ditches is the elongated green 

 Euglena viridis. In this animal one may notice a red 



. .., , _ . ,.,. , 



,--,' :'ti&---*--Z*:''?-'-r-&.,;-;,:..*SS' :, 9 .<'.:: -.:' 



^{S'vl ^i^v^^-'o' 9 r^k-. 

 ;;.:_ .>., ^rJ^YVJJ^.*..:-! .;-, 



.ii;-;;-io, 

 TO8& 

 " 



m>^ 



'..* '"':- \ 



>-: /A I 



.- x 



enec 



cv n * \ ./ 



Drawing by W. P. Hay 



FIG. 37. Amiba, magnified about 500 diameters, cv, contractile vacuole; n, nu- 

 cleus ; ec, ectoplasm ; en, endoplasm. The endoplasm contains diatoms and other 

 minute plants taken in as food and food masses in various stages of digestion and 

 assimilation. 



