CHAPTER III. 

 DERIVED ORGANIZATION. 



I. CYTOLOGICAL. 



PvVEKY protozoon, indeed every organism, has its own particular 

 fundamental organization. This is the specific aggregation of pro- 

 teins, carbohydrates and fats which, with the imbibition of water 

 containing salts of various kinds and oxygen, will undergo inter- 

 actions leading to the formation of substances and structures not 

 present before. The changes thus brought about furnish another 

 basic organization in which environmental stimuli, as well as stimuli 

 coming from within, cause interactions which result once more in 

 novel structures or substances. The organization thus is contin- 

 ually changing, each new organization on the basis of that laid 

 down before, until a structural stability results and further changes 

 cease. Such a series of changing organizations is what we usually 

 speak of as development or embryology or the transition through 

 varying phases from the fundamental to the derived organization. 

 Obviously with a given specific fundamental organization in the 

 same environment the successive changes will always be the same, 

 resulting in the same type of derived organization, and so a species 

 appears to be fixed in type. But different specific types of funda- 

 mental organizations have different potentials or possibilities of 

 development which result in different taxonomic types of organisms. 



With Protozoa the potential of development is relatively low, 

 but is higher in some groups than in others. Thus the structures of 

 a Paramecium caudatum or the endoplasmic structures of a Giardia 

 indicate a higher potential in these organisms than in Amoeba proteus. 

 But even in the latter there is a vast difference between an encysted 

 ameba and its actively streaming developed stage, and this differ- 

 ence is brought about by changes in the fundamental organization. 



The derived organization then includes the ordinarily invisible 

 structures which result from changes in the fundamental organiza- 

 tion, together with the ordinarily visible structures which furnish 

 the basis for classification. The latter for the most part are derived 

 from, or at least are intimately connected with, the former and 

 should not be separated from them. The former are included in 

 the present chapter under the caption Cytological characters', while 

 the latter are considered in the following chapter under the heading 

 Taxonom ic characters. 



Changes of the fundamental organization into the derived, occur 



