^ LIBRARY p* 



The Ottawa Naturalist. 



Vol. IX. _ OTTAWA, JULY, 1895. No. 4- 



CILIA. 



By PROFESSOR EDWARD E. Prince, Dominion Commissioner of Fisheries, Ottawa 



Anyone who has watched the minute organisms, seen in a drop of 

 pond-water under the microscope, must have been struck by the 

 extremely active motions of many of them. Simple in structure, and 

 destitute of limbs, they rush across at a furious rate, or glide smoothly 

 and swiftly in serpentine fashion, or spin round and round in endless 

 gyrations. How ate these astonishing movements produced? They 

 are due to cilia, the simplest and most insignificant of all organs of 

 locomotion. These organs are widespread in the animal kingdom, 

 though, curiously enough the Arthropods, that large class of animals 

 embracing crustaceans, insects, spiders, centipedes, etc., do not 

 possess them, so far as naturalists have been able to ascertain. As a 

 rule they are very small and abundantly scattered, but they may be 

 few and of considerable length, when they are then distinguished as 

 flagella, not cilia. A flagellum and a cilium are, however, structurally 

 and functionally the same. Flagella occur in plants as well as in 

 animals, and the spores of some algae art: so active, when swimming 

 about, that they may be readily mistaken for minute infusorian animal- 

 cule. Certainbacilli, too, possessone ormort flagella, and like the Monads, 

 the lowliest of all animal organisms, are able to progress with consider- 

 able speed. Noctiluca is a remarkable flagellate animal, like a small 

 particle of jelly. It swims through the water by means of its lashing 

 flagellum, and it often occurs in such countless myriads at the surface 

 of the sea, that being phosphorescent and able to admit light, the 

 waves are brilliantly illuminated over considerable areas. In contrast 

 to Noctiluca, we find that in Paramcecium, the commonest of ciliated 

 infusorians, minute cilia occur thickly all over the surface of the body, 



