The reactions of the flagellate Peranema

S. O. Mast
1912 Journal of Animal Behavior  
One figure Peranema is a colorless, cigar shaped flagellate scarcely 0.05 mm. long and but little more than 001 mm. in diameter. A prominent contractile vacuole is found near the "anterior end from which projects a heavy flagellum nearly as long as the body. Fig. 1 . It is a hardy, sluggish creature, usually found in abundance in cultures rich in decaying organic matter. I have kept specimens in excellent condition for three weeks on a slide under a cover glass sealed air-tight with vaseline
more » ... ht with vaseline These flagellates ordinarily move in contact with solid objects or on the surface film, but sometimes they swim through the water very much like Euglena. I shall refer to the former method of locomotion as crawling. The rate of motion by either method is relatively slow, the crawling rate being only 1 3-2.6 mm. per minute and the swimming rate but very little more Owing to this very moderate rate of locomotion it is a simple matter to follow under high magnification every movement the animal makes. In crawling, Peranema is frequently seen to continue for considerable distances in a fairly straight line It does not rotate as it does in swimming but proceeds with a given surface continuously in contact with the substratum to which it adheres with considerable tenacity, probably by means of secreted mucus. The flagellum. extends straight forward and is rigid and motionless except for about one-sixth of the whole at the tip, which is bent at right angle so as to form a sort of hook, Fig. 1 . This bent part of the flagellum vibrates rapidly, striking backward and forward in such a way that the free end describes a narrow ellipse. Thus the creature is literally drawn slowly and steadily along. This is the method of locomotion that is ordinarily seen but if the animals are strongly stimulated, as by the addition of a little iodin, marked wave-like contractions are seen to pass over the body from the posterior to the anterior end. That this wave-like contraction is at least at times func-91
doi:10.1037/h0072097 fatcat:q445aih34vavlpjcec7ic76cyi