26 MORPHOLOGY AND CULTURE OF MICROORGANISMS 



grain. The centriole is united to the blepharoplast by a centrodesmose t 

 the rhizoplast, which is often absorbed. Finally, the last centriole 

 situated beyond the blepharoplast about equally .distant, also unites 

 with this cell-organ by a centrodesmose and, by approaching the 

 extremity of the cell, causes the elongation of the centrodesmose which 

 transforms itself into a flagellum. 



In the infusoria the vibratile cilia insert themselves in the ectoplasm 

 and pass through the cuticle to reach the exterior. At the point of 



tr 



FIG. 16. FIG. 17. 



end 



FIG. 16. A, Spongomonas uvella. The nucleus is undergoing mitotic division. 

 Two centrioles, each at the base of a flagellum, are located at the two extremes of 

 the spindle. (After Hartmann and Chagas.) 



B, Monas termo. The cell lies in repose; a centriole (a) lies at the base of the 

 flagellum; in (C) there are two centrioles, in (D) the two centrioles occupy the two 

 poles of the nucleus during the process of mitosis; in (E) exists the final nuclear 

 division. (After Martin.} 



FIG. 17. Fragments of the peripheral portion of Prorodon teres (infusorian) 

 with vibratile cilia and their basal corpuscles, (ect) Ectoplasm; (end) endoplasm; 

 (tr) trichocysts. (After Maier and Gurwitch.) 



insertion of each of these cilia is a small chromatic corpuscle or basal 

 grain, a trichocyst, also supposed to arise from a repeated division of 

 the centriole (Fig. 17). 



The centriole which, as we shall see later, seems to be a motor 

 organ associated with the internal cytoplasmic movements during 

 cellular division, appears also to be connected with the external move- 

 ment of the cell. 



