HABITS AND REACTIONS OF LACRYMARIA 241 



cilia on a mechanical basis we must assume a corresponding 

 change in structural or physiological differentiation in the tis- 

 sue within the organism. The direction of turning cannot be 

 accounted for on the assumptfon of a fixed differentiation as it 

 can in Didinum, Q^dogonium and many other lower organisms. 

 What this internal regulatory change consists of is a problem 

 for further investigation. 



REPRODUCTION 



Lacrymaria reproduce by dividing crosswise near the middle 

 into two parts. No apparent change takes place in the two ends 

 of the dividing individual during the process of reproduction. 

 The anterior end of the mother becomes the head and neck of 

 one of the daughters and the opposite end becomes the posterior 

 end of the other. The endoplasm continues to surge back and 

 forth through the gradually decreasing opening between the 

 daughters whenever there is a sharp turn or a contraction in 

 either until but a short time before they separate, showing that 

 this substance does not necessarily divide equally. 



The activities and reactions of dividing indi\'iduals are essen- 

 tially like those in individuals not dividing. The movements 

 and reactions of both daughters, until they have actually 

 separated, appear to be regulated almost entirely by the activ- 

 ities of the head and neck of the parent. 



Lacrymaria like most of the other protozoa conjugate. Two 

 individuals after having decreased in size until they are not 

 more than half as long as ordinarily, come together and fuse 

 temporarily at the oral ends with the necks stretched out to a 

 length about equal to that of the body. While they are thus 

 united they swim about actively, but there is no coordination 

 in their movements as there is in conjugating Paramecia. Both 

 individuals respond to stimuli independently. This leads to all 

 sorts of fantastic movements. One frequently sees the bodies 

 of the conjugating specimens following each other round and 

 round in a circle, held on their course by the necks which extend 

 to the center where they are united. Through these two long 

 necks the nuclei must pass in the interchange of germinal sub- 

 stance preceding the process of fertilization. The regulation 

 of the movement of the nuclei in travelling this comparatively 

 great distance constitutes an interesting problem. 



