2S0 The Unity of the Organism 



Comparison of the Structure of Organisms Consisting of a 

 Single Cell with That of Organisms Consisting 



of Many Cells 



This chapter will be concerned primarily with the factual 

 side of the structure of the cell viewed as a species of or- 

 ganism, and will confine itself to the structure of the cell 

 in organisms indubitably such in the strict sense, even 

 though they ordinarily consist of but a single cell. 



The narrowing influence of elementalism in biology finds 

 striking illustration in the application of the cell-doctrine 

 to unicellular organisms, that is, to the protozoa and the 

 protophyta, or collectively, the protista. In fact, if one 

 wishes to bring before him in the clearest possible fashion 

 the contrast between what a great province of living nature 

 is when seen as it actually is and when seen through the 

 medium of elementalist theory let him compare some of the 

 great modern objective treatises on the protozoa, like Brady's 

 report on the Foraminifera and Haeckel's on the Radio- 

 laria, in the Zoology of the Challenger Expedition, or 

 Haecker's Tiefsee Radiolarien, in Wisse7ischaftliche Ergeh- 

 nisse der dewtschen Tief see-Expedition, with the statements 

 one finds in ordinary text books of zoology concerning the 

 same organisms. Hardl}^ anything could be more mislead- 

 ing than the almost universal practice in elementary teach- 

 ing of introducing beginners to the protozoa by showing, 

 very superficially, an amoeba and emphasizing its simplicity, 

 and then keeping it in the foreground of the learner's 

 thought as an exemplification of the doctrine that the pro- 

 tozoa are "extremely simple" animals, that they are undif- 

 ferentiated into organs and tissues^ — tliat in fact they are 

 hardly "true animals" at all. In even so advanced and usu- 

 ally excellent a work as Lang's Lehrhuch der vergleichenden 

 Anatomie we are told that the metazoa or "true animals" 

 {echte Tiere) are "set over against the protozoa or pro- 



