THE INFLUENCE OF GLANDULAR EXTRACTS 



UPON THE CONTRACTILE VACUOLES OF 



PARAMECIUM CAUDATUM. 



MARY DRUS1LLA FLATHER. 

 FROM THE BIOLOGICAL LABORATORY OF BRYN MAXVR COLLEGE. 



Contractile vacuoles have long been puzzling morphological 

 elements in the Infusoria. In general they may be said to be 

 cavities in the protoplasm destined to expel by contraction tin 

 liquid which they accumulate. They are present in all ciliated 

 infusorians except a few salt water and parasitic forms, but since 

 this paper deals prinlarily with the physiology of the vacuoles in 

 Paramecium caiidatum a description of their structure will be 

 limited to this species. 



Normally Paramecium caudatum possesses two contractile 

 vacuoles situated in the ectoplasm, one at the posterior end and 

 the other about mid-way between the anterior and posterior ends. 

 Cases have been noted by Hance (11) where a race seemed to 

 show a tendency toward multiple vacuoles, and by Shumway 

 (26) where the individual appeared to be stimulated to the pro- 

 duction of extra vacuoles by some abnormal physiological in- 

 fluence. Invariably the vacuoles are arranged in a straight 

 line. Each vacuole is composed of a central reservoir with 

 peripheral canals radiating from it, tin- number of canals varying 

 with the individual vacuole. The mechanism of contraction is 

 as follows. The canals swell slowly, then discharge their fluid 

 contents into the reservoir, which in turn contracts, expelling its 

 contents to the outside through an excretory pore. In systole 

 the reservoir disappears completely from view, leaving clearly 

 visible the rosette .of canals slowly filling again. A new cavity 

 must be formed by contraction of the canals in the protoplasm 

 which has replaced the old reservoir. The outline of (his new 

 reservoir is irregular at first, but gradually assume.^ the >hape of 

 the circular vacuole. The canals are simple allerent tubules 

 which pulsate twice to every contraction ol (he vacuole and 



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