PROTISTA. 27 



aggregation of atoms ; and that if Briicke says, " Apart 

 from the molecular structure, we must also ascribe to 

 living cells another structure of a different order of com- 

 plexity, and this is what we denote by organization," 

 we must likewise ascribe this yet unknown combination 

 to the Monera of Haeckel. 



But independently of this complexity of the molecular 

 structure, it is of extreme importance to the investiga- 

 tion of animate nature to have become acquainted with 

 bodies which present the simplest structure to the as- 

 sisted eye, and to anatomical research. The substance 

 which characterizes them is found again in plants as 

 well as in animals ; and plants and animals must now 

 be regarded as two classes of organisms, in which the 

 processes of self-preservation and reproduction have, in 

 different ways, assumed the character of a higher com- 

 plexity and development, by the differentiation of the 

 originally homogeneous substance into various morpho- 

 logical structures and organs. 



As we shall have another opportunity of expressing 

 an opinion in regard to the beginnings of animal life, 

 and its points of contact with protista and plants, we 

 shall transfer ourselves from the dubious boundary line 

 into the midst of the animal kingdom, in order to master 

 our subject by sifting and arranging it. 



The first impression of infinite variety is succeeded by 

 another, that there are lower and higher animals. On 

 this point complete harmony prevails. For if, from teleo- 

 logical considerations, invalid in our eyes, the nature of 

 every creature were said to be perfect, that is, in corre- 

 spondence with its purpose or idea, every one takes it for 

 granted and self-evident that a standard of excellence 



