INHIBITION OF LOCOMOTION IN PARAMECIUM AND 



OBSERVATIONS ON CERTAIN STRUCTURES 



AND INTERNAL ACTIVITIES. 1 



CHARLES E. BILLS, 

 ZOOLOGICAL LABORATORY OF THE JOHNS HOPKINS UNIVERSITY. 



The study of Paramecium under magnifications sufficiently high 

 to permit of observations on the activities within the living organ- 

 ism has been considerably hindered in the past by the excessive 

 motility which this protozoon exhibits. A number of methods, 

 physical and chemical, have been employed in attempting to over- 

 come this difficulty; yet all of these methods are open to the objec- 

 tion that they are transient, or that they hinder the observation of 

 certain activities, or even that they are severely limited in their 

 application by the sensitiveness of the organism to protoplasmic 

 poisons and osmotic changes. 



Of the physical methods for quieting paramecia the following 

 may be mentioned : ( I ) entanglement in zooglea or other debris ; 

 (2) retardation of locomotion in gelatinous media; (3) inactiva- 

 tion at low temperature. The objections to these methods are 

 patent : Entanglement affords an occasional arrest of activity ; but 

 in the infrequent cases where it is by chance efficient the animal is 

 often obscured from view. Retardation in such media as quince 

 seed jelly or gelatin is effective only when the gel is sufficiently 

 thick to prevent the entrance of food particles at the peristome, in 

 which case observation on this activity is impossible. Chilling 

 may greatly reduce locomotion, but internal movements are at the 

 same time unavoidably retarded. 



The chemical narcotizing agents in general use for the lower 

 animals are also in certain respects unsatisfactory for Paramecium: 

 Methyl alcohol and chloral in concentrations sufficiently high to 

 give any noticeable effect render the animal abnormal in appear- 

 ance before paralysis sets in. Ethyl alcohol is open to the same 

 objection, though to a less degree. Chloretone in concentrations 



i This paper was prepared under the direction of Professor S. O. Mast. 



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