235] STUDIES ON GREGARINES WATSON 25 



protomerite tends to straighten it; if half a dozen or more are formed 

 in a circle around the anterior end of the deutomerite, the protomerite 

 will sink into the central depression and often be obscured from sight. 



The parasite is able to move through a place much narrower than 

 the width of the body by the contraction and expansion of the epicyte, 

 as in the instance of an amoeba. 



Bending movement when the animal is out of its normal habitat 

 may be due to external stimuli such as the endeavor to avoid light and 

 the water medium. When in the normal habitat, the animal does not 

 need to move about in search of food, there is no light to avoid, and the 

 chief function of the bending movement when the parasite is in the in- 

 testine is probably the formation of a cyst. Two animals rotate about 

 an imaginary axis coming closer and closer together by bending more 

 and more, and finally form a perfect sphere (see Figures 234, 235 and 

 238 J. The formation of cysts by the use of normal saline occurred in 

 twenty-five minutes. The salt solution was removed as soon as the cyst 

 was completely formed and the cyst washed with distilled water. It de- 

 veloped to completion with the exudation of ripe spores. Cysts have, 

 however, developed in but little longer time in distilled water. 



SUMMARY 



1. Normal salt solution is the best artificial medium in which to study 



motion. 

 2., Locomotion is effected by means of a progressive, gliding movement 



with no apparent localized motion of the body. 



3. Progression takes place at the average rate of 0.8 per second in 



Leidyana erratica. 



4. In artificial media there are formed gelatinous threads at the pos- 



terior end of the deutomerite. 



5. These threads may be seen with a high power and a minimum 



amount of light in a mount which has been made for some 

 time. 



6. They do not occur in a freshly made mount. 



7. The threads may be demonstrated with carmine granules in sus- 



pension. 



8. The animal probably moves by imperceptible vertical movements of 



the myonemes of the side which is ventral at the time, and upon 

 a surface whose friction is caused by an exudation of slime 

 from the body of the parasite. 



9. This mucus is secreted by the body and runs out through pores be- 



tween the longitudinal ridges in the epicyte. 



