260 



THE AM ERIC AX XATCRALIST 



[Vol. L 



both in Woodruff's culture and in my Didinium culture, 

 and one general problem is stated in the query: how long 

 can such periods of reorganization continue? Woodruff 

 believes that they may keep on indefinitely, but in my ex- 

 periments with Didinium the race apparently lost its 

 power to encyst and ultimately died out after six months' 

 culture without encystment. So too, in my culture of 

 Paramecium anuhitum (11>02) where similar reorganiza- 

 tion occurred at least twice, the race ultimately lost the 

 power to reorganize and died out. I may have had un- 

 favorable forms to start with and so lost both races at 

 early dates. It is interesting in this connection, however, 

 to note that Whitney, working with the rotifer Hi)<taiiaa, 

 a metazoon, carried a race through nearly 200 generations 

 by parthenogenesis when the individuals lost their power 

 to reproduce in this way, and many of his lines died, while 

 others produced sexual individuals. 



The general biological effect of this process of reorgan- 

 ization is a new chemical combination with a new potential 

 of metabolic activity, and a new lease of life. Not only are 

 the nuclei restored to activity, but the cytoplasm is like- 

 wise completely reorganized by the distribution through 

 it of relatively large quantities of nucleo-proteins, giving 

 rise to successive derivatives (through hydrolysis, oxida- 

 tion, reduction, etc.), all increasing the metabolic processes 

 and releasing more chemical energy expressed by activity 

 of movement and feeding, and leading to more rapid as- 

 similation and growth, all indicated by an increased divi- 

 sion rate. In short, the protoplasm is rejuvenated. 



The second phase in the life history to be considered, 

 viz., the sexual phase, involves still more deeply-reaching 

 protoplasmic activities. The protoplasm of the'individual 



protoplasm becomes sticky or glutinous so that two 



d has a different physical, and presum- 

 ike-up than during ordinary vegetative 

 -living forms, such as the filiates, the 



igation is possible, 

 rtreme that groups 



