BEHAVIOR OF LOWER INVERTEBRATES 369 



is that of oars, not screws. The movements which they describe 

 may be classed under six heads, chiefly dependent on the form 

 and flexibility of the flagella. 



Mast's (19) description of the movements of Lacrymaria is 

 known to the readers of this journal. Its most significant con- 

 tent is perhaps the assertion of the random and unoriented 

 character of the movements. The direction of locomotion is 

 regulated by the movements of the head, which seem to be 

 wholly dependent on internal factors. The only evidence of 

 orientation is that " stimulation of the anterior end may not 

 only cause contraction of the neck but also backward movement 

 of the entire organism, while stimulation of the posterior end 

 usually causes forward movement." 



The paper by Day and Bentley (5) on learning in Paramecium 

 also appeared in this journal, and therefore needs but brief 

 notice. The method was practically the same as that used by 

 Stevenson Smith, although it was independently developed by 

 Day and Bentley ; it consisted in placing an animal in a capillary 

 'tube too narrow for it to turn in by the ordinary method of 

 darting backward and turning through an acute angle. A 

 record was kept of the number of efforts it made by this method 

 in successive experiments, before it varied the method and 

 escaped by bending its anterior end. The number of unsuc- 

 cessful movements and the time occupied by them was reduced 

 in successive trials, showing learning. Precautions were taken 

 against the effects of a chemical change in the medium such as 

 the accumulation of carbon dioxide. 



The articles by Jennings (15) and Woodruff (33) are con- 

 cerned rather with general physiological processes than with 

 behavior. Jennings, however, describes with some minuteness 

 the process of conjugation in Paramecium. The first contact 

 is at the anterior tips, which interlock. The period of "fitting" 

 is one of great and varied activity; there are bendings and con- 

 tractions, as if the animals were making efforts to bring the 

 mouths together. If they do not fit properly they separate, 

 and thus "assortative mating" occurs. Woodruff notes that if 

 a normal medium is supplied Paramecium caudatum can repro- 

 duce indefinitely without conjugation or artificial stimulation. 



Coelenterates. Schmid (30) finds that in darkness, Cereactis 

 aurantiaca withdraws its tentacles and stretches out its body. 



