Organisms Consisting of One Cell S67 



possibility as to size or as to simplicity of structure. This 

 examination of the protista brings into clear light a diffi- 

 culty not otherwise recognizable in the way of applying the 

 cell-theory to this section of the living world. The con- 

 cept cell being })rimarily one of structure and only second- 

 arily one of function, necessarily becomes inapplicable to 

 invisible beings so far as special objectivity is concerned, 

 while the concept organism being primarily one of function 

 and only secondarily one of structure, is quite as applicable 

 to invisible as to visible beings if, as in the case of disease- 

 producing microbes, we have observational evidence on the 

 functional side of their nature. No discoveries in the whole 

 biological realm have more clearly revealed the fatuousness 

 of the claim made by the cell-theory to being the "key 

 to all biological problems," than have those establishing 

 the existence of barely visible and invisible living things. 

 On the other hand, these discoveries taken along with those 

 concerning the structure of the protozoa and visible bac- 

 teria, have contributed greatly to the expansion and clar- 

 ification of the organismal conception. 



B. DEVEI.OPMENT 



False Concejjfions About Development in Protozoa 



We have now seen something of the disastrous effects of 

 trying to squeeze the whole adult structure of the pro- 

 tozoan into the theoretically "simple cell." It remains to 

 look at the still worse effects of trying to keep the facts 

 of development of the individual protozoan down to the 

 same theoretical limitations. We will first examine the no- 

 tion constantly inculcated by text-books and in formal in- 

 struction, that there is "no true developm.ent" in these crea- 

 tures. Embryology is almost always defined and treated so as 

 to exclude from Its scope development in the protozoa. Thus 



