396 JULIA ELEANOR MOODY 



eiit times. These reactions may be accounted for by an ex- 

 planation on the basis of chemical or physical laws of attraction 

 or by assigning to the organism something akin to intelligence. 

 The question naturally suggests itself, how has the exercise of 

 choice become limited to one special form of food material in 

 the case of Actinobolus and Spathidium? If, as Jennings 

 claims, the avoiding action of the cilia in Paramoecium is in 

 itself an expression of choice, it is not difficult to conceive of 

 a still further development of this expression as illustrated in 

 the reversal of the ciliary current, the bending of the body 

 of the organism and the swimming away from foreign substances 

 or undesirable food material. Accepting the definition of instinct 

 as purposive action without consciousness of purpose, it seems 

 legitimate to apply the term in this sense to the phenomena 

 involved in the food taking behavior of protozoa. The word 

 thus used is simply a convenient term for expressing the outward 

 manifestation of a relation existing between the protoplasm 

 of an organism and an external stimulus or another form of 

 protoplasm possessed of different chemical or physical proper- 

 ties. It may be that the behavior of the early ancestors of the 

 hunter ciliates was based on the method of trial. In the course 

 of time, the protoplasm of the organism has become modified 

 chemically and physiologically to such an extent that a reaction 

 to one kind of protoplasm only is possible — in other words 

 forms like Actinobolus and Spathidium have become 'educated' 

 through 'error' to the selection of one species of food, namely, 

 Halteria grandinella and Colpidium colpoda. 



March 9, 1912 



LITERATURE CITED 



Balbiani', E. G. 1889 Recherches exp^rimentales sur la merotomie des in- 

 fusoires cilies. Recueil Zool., Suisse, torn. 5. 



1891 Sur les r6g6n6rations successive du ijoristonie chcz les Stentors 

 et sur la role du noyau dans ces ph6nomene. Zool. Anzeiger, Bd. 14. 



BovERi, T. 1905 Zellenstudien V. Ueber die Abhangigkeit der Keingrosse 

 und Zellenzahl der Ausgangszellen. 



Brandt, H. 1877 tJber Actinosphaerium Eichhorni. 



