36 



THE SMALLEST LIVING THINGS 



organization is consequently static. But such static protoplasm 

 has the possibility of activity when the proper condition is pro- 

 vided — when water is added it becomes dynamic. It is not 



Fig. 176— SECTION OF AN 



ENCYSTING SPECIMEN 



OF DIDINIUM 



NASUTUM 



The old macronucleus has fragmented 



into many pieces, which are not yet 



absorbed 



From a photomicrograph by the author 

 Magnification, 1000 



correct, therefore, to state that life is dynamic, or that life and 

 activity are synonymous. Without organization, activity is im- 

 possible, but our encysted unicellular organism shows us that 

 organization is possible without activity. Hence living matter 

 may be regarded either as protoplasmic organization in action, 

 or as organized protoplasm in a static condition with the pos- 

 sibility of action. 



Individuality Unchanged by Encystment 



Another point is illustrated by our encysted organism. Since 

 all external structures characteristic of the active individual are 

 lost with encystment (Figs. 17 a and 17 b) there are no visible 

 structures to indicate what type of organism is represented by 

 any cyst. Yet no two cysts are alike, although they may be 

 indistinguishable to all but a specialist. If we watch individuals 

 of x and y species encyst, and after some days or months, during 

 which the x cysts cannot be distinguished from the y cysts, observe 

 these organisms emerge, we find that x individuals never emerge 

 as y but always as x, and y cysts always produce y individuals 

 only. This means that the organizations of the x and the y 

 cysts, although made up of protoplasms, which, when analyzed, 



