In Paramaecium, digestion occurs in the food vacuoles which circulate in the endoplasm along a definite path. This circulation of food vacuole is brought about by the rotatory streaming movements of cytoplasm termed as Cyclosis and is completed in 2 to 3 hours. This path is functionally equivalent to an alimentary canal.
Types of Paths followed
There are two kinds of paths that are followed by vacuoles.
1. 8 – shaped Path
After detaching itself from the cytopharynx, the food vacuole first goes around the cytopharynx and then pass forward to the anterior end, then move to the posterior and again pass forward to finally reach the anus.
2. 0 – shaped Path
From the cytopharynx, the food vacuole passes backward to the hind end, then move forward to the anterior end and finally backward to reach the anus.
Thus, we can say that cyclosis is a rotatory streaming movement of the cytoplasm in Paramaecium that helps in moving around the food vacuole.
- Anderson, Donald Thomas. Invertebrate Zoology. Oxford Univ. Press, 1999.
- Dhami, P. S, and J. K Dhami. Invertebrate Zoology. R. Chand, 1981.
- Kotpal, R.L. Modern Textbook of Zoology. Rastogi Publications, 2014.