REACTIONS OF OPALINA RANARUM 



By ELSA SHADALL 



University of Wisconsin 



1. INTRODUCTION 



Although the anatomy and reproduction of Opalina ranarum 

 have been carefully studied, the reactions of this mouthless 

 entozoic infusorian have not been so thoroughly investigated. 

 Probably the most comprehensive recent work is that of Met- 

 calf ('09) who gives a splendid chronological review of the litera- 

 ture. The first account, however, which deals with reactions, 

 is that of Kuhne ('59) who describes the effect of a strong in- 

 duction current on Opalina. Several years later, Nussbaum 

 ('86) briefly described the structure and the method of swimming 

 in the introduction to his theme on reproduction. In 1888, 

 Entz worked on light reactions and concluded that Opalina 

 was negative to light. A year later, Verworn ('89) obtained 

 results on the effect of light which were exactly opposite to 

 those of Entz. Verworn treats also of reactions to heat stimuli. 



Experiments in galvanotropism were performed by Birnkoff 

 ('99), Putter ('00), Kolsch ('02), Wallengren ('03), and Hartog 

 ('06). Dale ('01) gives the most detailed account yet published 

 of chemotaxis and describes very carefully the movement of 

 cilia and their behavior to chemical and electrical stimuli. Vene- 

 ziani ('04) experimented with culture media of varied chemical 

 composition and showed the effect of each on Opalina. His 

 work was continued by Putter ('05) who discovered that a medium 

 prepared from sodium chloride, sodium and potassium tartrate 

 and distilled water was best. The work of Jennings ('06) con- 

 cludes the list of publications on the behavior of Opalina. 



Opalina is a large ovoid protozoan completely covered by a 

 pellicle and therefore without mouth or anus. 1 It is strongly 



1 Some of the earlier investigators (Kiinstler, '06, and Gineste, '06) claimed that 

 a minute mouth was present on the ventral surface of the body, but their view 

 has not been accepted by recent observers. The writer has made every effort 

 to discover such an opening but without success. Specimens stained slightly with 

 Delafield's haematoxylin and placed in a thin solution of gelatin afford excellent 

 opportunity for observation but nothing could be discovered except little evan- 

 escent folds which frequently appear when the body is in the proper position. 



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