THE RABBIT. 



39 



(known as desmids and diatoms) which are almost as simple 

 in their own way as amoeba is in its, but still distinctively 

 plants, as amoeba is distinctively an animal. When the 

 protoplasm of an amoeba comes in contact with one of 

 these, it quickly flows round it, and completely encloses or 

 ingests it. In a well-fed amoeba, three or four or more of 

 these plants may be seen the recently ingested ones bright 

 green in colour ; others that have been longer enclosed are 

 brown, and otherwise show signs of partial digestion. Not 

 unfrequently, in watching a living amoeba, we may 

 witness the ejection of the indigestible residue of these 

 plants from which the nutritive material has been extracted : 

 " ejection," however, is too strong a word we may rather 

 say that the amoeba flows off and abandons the useless 

 residue. 



3. Nucleus and Contractile Vacuole. When an 

 amoeba does not contain much food in process of digestion, 

 two other structures present in the endoplasm can be more 

 easily seen. One of 

 these is a spherical 

 body, evidently firmer 

 than the rest of the 

 protoplasm : this is 

 called the nucleus. 

 The nucleus is a 

 structure of the 

 utmost importance to 

 the amoeba proto- 

 plasm from which 

 the nucleus has been 



Fig. 6. AMCEBA. 



removed may remain 



alive for some time, but is incapable of carrying on the 



most essential vital functions. 



The other structure seen is a spherical cavity in the 

 protoplasm, containing some liquid. This slowly increases 

 in size by the collection of more liquid in it, and then quite 

 suddenly collapses with just the same appearance that is 

 presented by a bladder full of water when it is pricked. 

 Soon it reappears at the same spot and gradually grows 



CO*nr*ACTtL 

 VACI/OLC 



