242 The Structure of Protoplasm 



Especially helpful in an analysis of the effect of an external agent on 

 protoplasmic reactions is a study of two dynamoplasmograms, one 

 obtained from a plasmodium which had been treated in entirety by 

 an external agent, and the other obtained from a plasmodium of 

 which only one-half was subjected to the same agent. The latter con- 

 dition is easily accomplished by using the double chamber, the exter- 

 nal agent being applied only to one compartment and therefore, only 

 to one-half of the plasmodium. As a result, the plasmodium under- 

 goes a modification in polarity. The dynamoplasmograms plotted 

 from this, show that very often the whole wave is shifted to one side 

 of the base line without crossing it, but the rhythm continues. 



Phenomena known as taxis, such as chemotaxis, phototaxis, 

 thermotaxis, rheotaxis, galvanotaxis, etc., have been studied in 

 slime molds by many research workers since the last century. All 

 taxic movements, no matter what kind they may be, result from the 

 polar nature of the motive force. A change in polarity due to 

 unequal distribution of external factors can be very exactly por- 

 trayed on the dynamoplasmogram on the quantitative basis. The 

 half-treatment-dynaTnoplasviogram offers interesting problems when 

 studied in comparison to the whole-treatment-dynamoplasmogram. 



XII. RHYTHMICITY AS AN ATTRIBUTE OF PROTOPLASMIC ACTIVITY 



It was stated that the rhythmic motive force does not disappear 

 even though the movement is arrested for a period of time. From 

 this fact one can assume that the displacement of protoplasm by 

 streaming can play no part in the causal chain of the mechanism of 

 reversal. Rhythmic mechanism has, therefore, nothing to do with 

 the relation of action and reaction brought about by the flowing 

 of protoplasm. Thus, the views which postulate that a possible 

 physical or chemical change accompanying the change in distribution 

 of protoplasm is the cause of the reversal may be discarded in the 

 light of the above findings. Rhythm is a more deep-seated attribute 

 of protoplasm. 



The rhythmic activity of protoplasm discussed in the present 

 paper is concerned only with slime molds. It is, however, a question, 

 and an important one, whether or not polyrhythmic nature is the 

 specific attribute of slime-mold protoplasm or whether it is essentially 

 universal and, therefore, occurs in other protoplasmic systems. The 

 fact that a visible form of movement does not show periodicity can 

 not offer any cogency to the argument that the basic motor mechan- 



