INTRODUCTION 



structures such as elastic capillitia for dispersion of the spores. The 

 relation to the Protozoa, on the other hand, is claimed on account of 

 the unicellular nature, development of the swarm-spores, and occa- 

 sional holozoic mode of nutrition. The spores leave the sporan- 

 gium as amoeboid or flagellated organisms and may increase by 

 simple division during the swarming stage. If flagellated, the spore 

 after a time loses the flagellum and becomes amoeboid, in which con- 

 dition division may again occur; finally numerous amoeboid indi- 



B 



Fig. 4 . _ Flagellidia. [STEIN.] 



A. Chrysomonas ( Chromulina) flavicans. Ehr. with chromatophores and an engulfed diatom 

 (d). B. The same encysted. C. Phacus longicaudus Duj. 



viduals group themselves together, forming a colony or plasmodium. 

 In some cases the fusion is complete, in others the outlines of the 

 individual Amoebae persist. 



In view of the questionable position which these forms occupy, 

 there is some danger of their being neglected altogether, the botan- 

 ists refusing them because of their animal characteristics, the zoolo- 

 gists because of their plant-like features. No harm can be done by 

 including them in both kingdoms, for on purely a priori grounds it is 

 to be expected that some organisms should be on the boundary line 

 between artificial groups such as the unicellular animals and plants. 

 The present group and the Phytoflagellida among the Mastigophora 

 appear to occupy such a position, and it is advisable to include them 

 as provisional groups of the organisms with which they show the 

 greatest number of common points. With our present knowledge, 



