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Lastly, let us consider the ciliary movements so commonly met 

 with in the zoospores, and some of the lower algse. Cilia are by no 

 means confined to the animal kingdom ; they consist of hair-like 

 prolongations from the surface of animal and vegetable bodies that 

 are bathed in fluid. During life and for some time after death, the 

 cilia are usually in constant movement, giving the parts of the 

 field of the microscope in which they are situated a tremulous 

 motion. They are large and easily seen in the gills of the common 

 mussel. In land vegetation cilia may be seen in all the higher 

 stem-forming cryptograms, in lycopodiacere, ferns, equisetaceoe and 

 mosses, and in the water plants, characeoe, algte, and others, upon 

 which they are found upon the filaments (spermatozoids) discharged 

 from the antheridia. The zoospores of vaucheria are clothed with 

 them over the whole surface. Perhaps the most interesting of 

 these is volvox glohator, now classed with the confervoid algte, 

 but for a long time regarded by iVaturalists as belonging to 

 the animal kingdom. Volvox is the largest species of its family, 

 averaging s^jth of an inch in diameter, it resembles a green sphere, 

 like a glass bubble filled with water, but studded all over with 

 small greeri spots at regular intervals, which give it its green 

 colour. Seen in profile, these spots which are the zoospores are 

 drop-shaped, the pointed end jiist penetrating the sphere, whilst 

 two delicate hairs (cilia) are seen to project from the pointed end; 

 By means of these the round sphere of the volvox is kept in 

 motion in the water. The cilia all act in concert, producing at times 

 a steady rolling motion, but occasionally the volvox stops and 

 changes its direction. Watching these pear-shaped zoospores with 

 a high power we notice a bright red spot (formerly called an eye) 

 and hollow spaces termed vacuoles, which have a curious power of 

 contracting at intervals of about forty seconds. If one of these is 

 detached from the parent sphere it will be seen to be exactly like 

 the form of the zoospore produced from other algse, and it moves 

 about in the water by the aid of these two cilia. Within the 

 volvox yoii may generally notice other rotund green bodies which 

 are liberated after a time when the parent cell bursts and sets them 

 free to live their own lives. Towards autumn, instead of these 

 green spheres being produced, spindle shaped ciliated bodies escape, 

 and coming to rest cimnge in colour and then move about, not by 

 cilia, but by bulging out in different directions, and thus they 

 make a slow progression, in fact become amoeboid. 



Having now dwelt on the movements in difPerent plants 

 belonging to all classes in the vegetable kingdom, I must bring this 

 long chapter to a close. We may learn from it many curious 

 points that connect the vegetable with the animal world. One at 

 least is apparent, that plants, though for the most part fixed, have 

 nevertheless in common with animals many modes and means 

 of movement ; moreover these are directed to accomplish a desired 



