HABITS AND REACTIONS OF LACRYMARIA 231 



as free in its movements we might see it thread in and out 

 among the branches, selecting choice morsels from any part 

 of towering monarchs of the forest and stripping them of their 

 foliage. 



REACTIONS OF ENTIRE ORGANISM 



Before discussing the mechanism by means of which the ex- 

 treme extension of the neck and the freedom of movement of 

 the head of Lacrymaria are regulated let us consider the move- 

 ments and reactions of the organism as a whole. 



Like nearly all of the flagellates and ciliates Lacrymaria rotates 

 on its long axis as it swims through the water, but owing to the 

 freedom of movement of the head and neck its course usually 

 varies greatly, much more so than that of any of the other mem- 

 bers of its class. It may be practically straight or it may be in 

 the form of a spiral of various widths, but it usually is extremely 

 irregular with the most fantastic curves in every direction. 

 Specimens are frequently seen to throw" the anterior end to one 

 side until it is nearly parallel with the body and then suddenly 

 turn and proceed in the opposite direction or at any angle to 

 the old course. Fig. 8. It is the movement of the head that 

 largely regulates the direction of movement of the body and the 

 movements of the head are almost entirely controlled by the 

 activity of the oral cilia. 



^ While swimming the creature frequently comes in contact 

 with the various objects found in the solution and is stimulated. 

 By carefully observing its behavior Avhen thus stimulated its 

 general method of response was worked out in detail. If the 

 head comes in contact with an object the organism may respond 

 in two or three different ways, depending upon the location 

 and the nature of the contact. 



(a) If the head strikes an object rather lightly and at an acute 

 angle the animal usually deviates from its course only enough 

 to slide by and avoid the obstruction. Thus specimens may 

 be seen to glide about through the interstices of a fibrous mass 

 turning in various directions without any apparent response. The 

 change in the direction of motion under such conditions appears 

 to be due entirely to the mechanical effect of the object on the 

 moving organism. It may be, however, that the oral cilia are 

 directly stimulated by the contact and respond in such a way 



