OF MICR O- OR GANISAIS. 1 3 



paralysed, while the fine and delicate cilia continue 

 their movements, which do not seem to be under the 

 influence of the will. These movements alone cause' 

 the whole body to rotate until the vibratile cilia are 

 in their turn paralyzed. 



Besides the cilia and the cirri, other appendages 

 in the form of membranes are found among the Infu- 

 soria, appendages which are attached to the anterior 

 part of the body or the peristome; these membranes 

 serve the purpose of causing eddies in the water, 

 which bring the floating alimentary particles into the 

 mouth. They are modifications of the vibratile cilia; 

 these membranes like the cirri are formed of aggluti- 

 nated cilia. 



The Flagellum. The study of the third organ of lo- 

 comotion, the flagellum, brings us to speak of the 

 class of Mastigophores and more particularly of the 

 group Flagellata. The Flagellates are Protozoa of 

 very small size, all in all, very much smaller than the 

 ciliated Infusoria. They have no vibratile cilia at all,' 

 but they are always equipped with one or more fila- 

 mentous appendages which have the form of a long 

 lash. This is the flagellum. This lash, like all the 

 organs of locomotion hitherto studied, has two func- 

 tions: it is at once an organ of locomotion and an 

 organ of prehension. The flagellum is most fre- 

 quently single or double (see fig. 4, representing the 

 Euglenadeses with its single flagellum); sometimes a 

 person can count a much larger number of them, four, 

 six, eight, ten, and more. As regards the insertion, 

 the same variations are met with. Sometimes the 

 flagella are very numerous and seem to be planted on 

 the same point of the surface of the body, thus forming 

 a brush or plume. In other species we find several 



