AMITOSIS IN CILIATED CELLS 111 



undoubted centrosome is discernible. The absence of a centro- 

 some, or its preemption as basal bodies by the cilia, would seem to 

 1)6 an adequate structural cause to explain the amitotic division 

 in ciliated cells, A relation between the formation of the ciliary 

 apparatus and the centrosome is at once suggested. The Len- 

 hossek-Henneguy hypothesis states that from the centrosome 

 by partition the basal granules are formed, and that from these 

 granules cilia are sprouted. It is very suggestive that the axial 

 filament of the fiagellum of the sperm (comparable to a coarse 

 cilium) does grow out from one of the two partition products of 

 the centrosome of the spermatid. 



Saguchi's description" of the centrosomes in ciliated cells of 

 the vasa efferentia of the mouse and the rat (pp. 254, 255), and 

 his illustrations, both indicate the difficulties and uncertainties 

 involved in an attempt to differentiate centrosomes from mito- 

 chondria and other cytoplasmic granules, and particularly from 

 the basal granules. Indeed, his description of the pluricorpus- 

 cular centrosome in the cells of the rat, 'curious ring-shaped cor- 

 puscles,' which he interprets as 'derived from the centrosome,' 

 stating that "a centrosome divides repeatedly and forms a ring 

 by secondary fusion of separated particles" (p. 255), would 

 seem to accord well with the interpretation of basal bodies as 

 derivatives of a centrosome. IVIoreover, both in the case of the 

 rat and of the mouse, Saguchi describes a diplosome in the non- 

 ciliated brush-border cells of the efferent tubules, the upper 

 member of which pair of centrosomes 'often bears a cilium' 

 (p. 255). These observations would seem to support the con- 

 clusion that basal corpuscles of ciliated cells are derived from 

 centrosomes; but Saguchi refuses to ascribe to them any such 

 significance. 



I find no relationship, other than spatial, between mitochondria 

 and the ciliary apparatus. Recent investigations on mitochon- 

 dria have demonstrated that these cytoplasmic elements ha\'e 

 no direct genetic relationship to structures such as nerve, muscle, 

 or connective-tissue fibrils, but are fundamental vital elements 

 of the cytoplasm, probably associated with metabolism. Sa- 

 guchi, however, concludes and asserts that cilia are formed from 

 mitochondria. Such a transformation would necessitate not 



