GENERAL PHYSIOLOGY 165 



which they pass and become stabile elements of the protoplasmic 

 make-up. Such changed substances no longer enter into the vortex 

 of vital activities, but as metaplastids may or may not be of further 

 use to the organism. 



The almost infinite variety of form and structure represented by 

 the Protozoa in the last analysis, must be traced back to the chem- 

 ical nature of the proteins and to their relations and interactions 

 with other substances in protoplasm. Types which have a similar 

 chemical and physical make-u]), with similar metaplastids and 

 plastids, are practically identical in form and structure and we 

 recognize them as distinct species. Variations in chemical com- 

 position, be they ever so little, must result in different chemical 

 reactions and products with corresponding variations in form and 

 structure of the organism, and these variations furnish the basis 

 for classification. 



Under normal conditions the reactions amongst the varied sub- 

 stances in protoplasm of the same species, with their products and 

 arrangement of these products, are individual and in\ariable. Fur- 

 thermore, the entire organism partakes of this indi\'iduality. A 

 fragment of Stentor obtained by cutting or by shaking cannot be dis- 

 tinguished from a similar fragment of Dileptus, yet the former regen- 

 erates into a perfect Ste)>t<yr, the latter into a perfect Dileptus. Or 

 an encysted Urolepfus mohilis is morphologically identical with an 

 encysted Didinium nasuhtm; both are apparently homogeneous balls 

 of undifferentiated protoplasm; the one emerges from the cyst with 

 the characteristic differentiations of Uroleptus, the other of Didin- 

 ium. In short, the homogeneous ball representing Uroleptus is as 

 specific and different from the homogeneous ball representing 

 Didiniinn, as the adult Uroleptus is different from the adult Didin- 

 ium. We may speak of this specific chemical and physical make-up 

 as the fundamental organization of the species, or of the specific 

 protoplasm, in a sense similar to the architectonik of Driesch. The 

 adult characteristics are the outcome of the specific chemical make- 

 up of the proteins, carbohydrates, salt, water, etc., and of the 

 interactions amongst them and represent what we may call the 

 derlred organization. 



Organization in the above sense is not only specific but con- 

 tinuous from generation to generation, and has come down through 

 the ages subject, however, to modifications and changes through 

 interaction with the en^■ironment or through changes coming from 

 within as in amphimixis. 



While organization is continuous the actions and reactions going 

 on within it are discontinuous. More or less prolonged periods of 

 rest are characteristic of all living things, best exemplified in the 

 case of spores, eggs, encysted Protozoa and seeds. At such times 

 the organization is static; the chemical substances making up the 



