22 Instinct and Intelligence 



simplest kinds of organism, such, for instance, 

 as the Amoeba proteus. 1 



Amoeba are of microscopic size, and may be 

 found moving about on the mud at the bottom 

 of many ponds and ditches ; each one of these 

 unicellular beings contains a single minute 

 speck of nucleated protoplasm. The proto- 

 plasm forming the substance of these unicellular 

 beings consists of a network of proteid ele- 

 ments, the interspaces being occupied by semi- 

 fluid contents. The Amoebae do not possess a 

 nervous system, eyes, locomotor, or any other 

 permanent organs; their nucleus, however, is 

 composed of a somewhat different variety of 

 protoplasm from that which forms the body of 

 the cell. The worn-out elements of these living 

 cells are replaced by metabolic processes (p. 17), 

 and it is thus supplied with a constant reserve 



1 For half a century the author of this volume has been more 

 or less occupied in studying, under the highest magnifying powers, 

 the life-history of some of the simplest organisms ; his attention 

 having been directed, when serving in India, to this subject in 

 an effort to define the specific germs which he was convinced gave 

 rise to Asiatic cholera. (A Treatise on Asiatic Cholera, by N. C. 

 Macnamara, Calcutta, 1869.; It would be out of place here to 

 recapitulate the results of his work, especially as reliable descrip- 

 tions of the behaviour of lower organisms, including that of the 

 Amoeba, are now at command, written by impartial and acknow- 

 ledged authorities in this department of science. (Prof. H. S. 

 Jennings, The Behaviour of Lower Organisms, New York, 1906.) 



