214 The Structure of Protoplasm 



periods. The alternation of waxing and waning periods is better 

 illustrated in Figure 7. During the periods of 9-13, 21-25, 32-36, 

 and 42-46 minutes on the abscissa, the waves have an increased 

 amplitude, and the shape approaches the harmonic wave. Between 

 any two of these adjacent wave groups, there are periods of decreased 

 amplitude where the wave form is irregular and clonic. The interval 

 of waxing and waning periods in Figure 7 remains approximately 

 constant for about 11 minutes; that is, the wave undergoes a similar 

 change in amplitude every 11 minutes. This is, however, not a 

 general rule, but applies only to the plasmodium used in this experi- 

 ment. The duration of the waxing and waning periods of a Plas- 

 modium, if any, differs from specimen to specimen; indeed, it 

 changes in one and the same plasmodium, as will be considered later. 

 Figure 8 shows a pattern similar to Figure 7, but the increase 

 and decrease of the amplitude takes place more frequently. Here 

 the irregular and clonic portions of the curve, which correspond to 

 the waning periods in the foregoing graphs, appear every 6-7 min- 

 utes, preceded and followed by only two or three smooth and reen- 

 forced waves. The patterns of the clonic parts of the waves are not 

 similar to each other. 



From the graph discussed above (Figs. 7 and 8), it is evident 

 that the waves undergo pronounced variations in amplitude and that 

 these variations occur according to a rhythmic pattern. It must be 

 noted, however, that the regular alternation between waxing and 

 waning periods can not be observed in all specimens of plasmodia. 

 The waxing and waning of the wave train often take place at vary- 

 ing intervals and to a varying extent. Figure 9 is an example of this. 

 The wave magnitude changes from rhythm to rhythm, but tonic and 

 clonic changes occur at irregular intervals. During the periods 0-6, 

 26-29, 55-70 minutes on the abscissa, the waves show a decrease in 

 magnitude. A similar tendency is also recognized, though less promi- 

 nently, during 16-19 minutes on the abscissa. On the other hand, 

 the wave groups between two of these depressed portions of the 

 curve are comparatively tonic. The constancy of the waxing and 

 waning periods is not maintained here. 



The foregoing graphs show that the motive force undergoes pro- 

 nounced variations not only in its magnitude, but also in its wave 

 form during the rhythmic succession of vital processes. Sometimes 

 a characteristic form appears repeatedly throughout several rhythms. 

 Even when an exactly similar wave form is not repeated, the change 

 is generally transitional in the course of the successive waves. 



