502 PROCEEDINGS OP THE AMERICAN ACADEMY. 



The evidence for the above view of adjustment is mostly indirect. 

 Where direct chemical analysis can give information of the internal 

 constitution of any particular protoplasm, the method of determining 

 adjustments would not be resorted to for that end. But where analysis 

 cannot be applied, or where the results of analysis give too little indica- 

 tion of the original active form of combination of the radicals found by 

 that process, the method of adjustments has considerable value. It is not 

 of value because of its accuracy, for it is only a method of approximation, 

 but it affords a wider physiological knowledge of substance-relations than 

 can be obtained by analysis alone. 



From the nature of the case we can adduce evidence of only a 

 general and probable character for the view of adjustment above out- 

 lined. In our experiments we found Stentor well adjusted to certain cal- 

 cium compounds and to certain phosphates. Other salts normally found in 

 various kinds of protoplasm, if added, improved the degree of adjustment. 

 It is probable that, had the experiments been longer continued the need 

 of these latter salts, though present in small proportion, would have 

 become more evident. All the salts used in the experiments upon 

 adjustment are found in the list of necessary salts as determined by 

 various feeding experiments, and also in the list of general protoplasmic 

 constituents as determined by chemical analysis. Further general evi- 

 dence comes from the consideration that the liquid medium is the sole 

 source of income and the sole recipient of the outgo of the metabolic sub- 

 stances of the cell. Under the circumstances a general correspondence 

 between medium and cell constitution could scarcely fail to exist, espe- 

 cially in the case of the physiological salts. That the metabolic activity 

 of the organism is a metamorphosing process is not inconsistent with the 

 above view. 



In the case of Stentor an interesting ecological problem suggests itself 

 in this connection. What relation is there between the adjustments which 

 the animal has shown in the laboratory and the conditions in regard to 

 substances which prevail in the natural homes of Stentor in the field ? 

 I have no data to present upon this subject, although it would be prac- 

 ticable to obtain such in this vicinity. 



I now turn to a brief consideration of the question, What relation 

 does the process of division in Stentor bear to the physiological salts? 

 The substances experimented with fall into two classes. In the one 

 stands solely potassic chloride. Of all the substances tried, it alone 

 seemed to have the power of specifically disturbing the process of divi- 

 sion. In what manner this was effected we are unable to say. All the 



