378 Causes and Course of Organic Evolution 



Animals as a rule respond quickly. 

 (5) Plants accordingly have not developed rapidly con- 

 tractile tissues except in some simple motile types, or in 

 sensitive and in related forms; nor have they developed 

 special sense centers nor nerves, except the sensory con- 

 ducting areas in root tips, stem tii)s, and leaves, be so 

 v-iewed as in rudimentary form. 



Animals have developed rapidly contractile tissues, and 

 nerves. In connection ^vith these and through energizing 

 activity of cogitic associated with cognitic and biotic as 

 well as the lower energies, nerve or ganglionic cells have 

 been evolved. 



If now we pursue a similar mode of treatment for animals 

 as has already been done for plants, in an effort to follow their 

 evolutionary trend, it may be well to trace their ecological 

 origin and gradual distribution over the world. A remarkable 

 similarity mth plants will be found to unfold itself, but one 

 that is widely at variance from many recently accepted views. 



Though it must be conceded that the Proteomyxa form a 

 highly heterogeneous and even doubtful assemblage, it seems 

 generally true of at least some of them that they are devoid 

 of, or possess only a rudimentary nucleus; that they are rather 

 sluggishly responsive to en\dronal stimuli; that there is no sex 

 differentiation, or only a commencing indication of it, where 

 the gametes aie similar to each other; and that multiplication 

 is by division, or by its modified method endogenous division. 



When we combine the accounts of Zopf, Rhumbler, Butschli, 

 and Calkins \^^th the classified list given by Hickson (82: 6), 

 it may be said that 30 genera, which include about 178 species, 

 are known. Of these 16-18 genera are fresh-water or parasitic 

 on land organisms, and they include about 120 species; 5 genera 

 are mainly found in like places, but include a few species that 

 are marine; 7 genera are marine, but include only 20-25 species. 



Study of the unicellular Caryozoa gives striking confirma- 

 tory results. We will review these in their probable evolu- 

 tionary' relationship, and accordingly will treat of the Lobosa, 

 the Mycetozoa, the Heliozoa, the Foraminifera, and the Radi- 

 olaria first, since all of these are naked pseudopodial oigan- 

 isms. Next the Mastigophora, the Sporozoa, the Hsemo- 

 flagellata, and the Infusoria which generally or always develop 



