166 BIOLOGY OF THE PROTOZOA 



specific organization are present but quiescent, or at most relatively 

 inactive. A striking illustration is afforded by the phenomenon of 

 desiccation in some types of animals, e.g., rotifers. For some years 

 I had on my shelf a bottle of minute amorphous granules which 

 appeared like specks of dust under the microscope. After placing a 

 few of these granules in water each of them would become an active, 

 living rotifer in an hour or so. Here organization was present 

 l)ut inactive and activity began with the absorption of water and 

 with oxidation. The rotifer in the active state is the same rotifer 

 that it was in the dried condition, so far as organization is concerned, 

 but it dift'ers in that the organization is now in action. It is a 

 dift'erence of the same nature as that between an automobile stand- 

 ing in the garage, and the same automobile tra^'elling 30 miles an 

 hour. The organization is in action in both moving rotifer and mov- 

 ing automobile; is static in the dried rotifer and in the standing 

 machine. 



For descriptive purposes, at least, we find a decided advantage 

 in a clear discrimination between these two states of living matter, 

 viz. : organization in the quiescent or resting condition, and the 

 same organization in action. We would limit use of the term 

 Vitality to the active state and would define it as the sum total 

 of actions, reactions, and interactions going on between and amongst 

 the substances making up protoplasm and between these and the 

 environment. The concept Life, with its attribute of continuity, 

 thus becomes associated with the concept of organization rather 

 than with the more dynamic concept of activity, which is inter- 

 mittent or discontinuous. Life cannot be defined or measured 

 any more than we can define and measure organization. Vitality, 

 on the other hand, can be measured both as a whole and in its con- 

 stituent activities. 



As a result of activities the protoplasmic organization itself may 

 change. An encysted Uroleptus is a motionless and apparently a 

 homogeneous ball of protoplasm; an hour later it is an elongate, 

 cigar-shaped organism with specialized motile organs in the form 

 of cilia, meml)ranelles and cirri, and its contractile vacuole pulsates 

 with rhythmical regularity as it moves actively about in the water. 

 The organization has undergone a change in this brief period; the 

 first indication is the swelling and enlargement of the cyst wall, 

 evidently by the absorption of water; oxidation probably occurs and 

 substances already present, or new substances formed as a result 

 of this initial oxidation, are responsible for the newly-developed 

 structures or derived organization not present before. Such struc- 

 tures, however, are the morphological expression of the adult organ- 

 ization and their formation corresponds to development and differ- 

 entiation of the metazoon egg. 



Continued activit\^ involves other and still more subtle changes in 



