262 S. SAGUCHI 



with two nuclei in the epididymis of various vertebrate animals, 

 in the trachea of the cat, in gills of Unio, and he believes that 

 these nuclei are produced by amitosis which is connected with 

 the following cytoplasmic division. He expresses himself re- 

 garding the cause of amitosis in ciliated cells as follows: "The 

 fundamental cause of amitotic cell division in cihated cells is 

 the destruction of the centrosome in the formation of the basal 

 bodies from which the ciha develop." Contrary to the view 

 of this author, Henry ('00), Ach ('02), Ikeda ('06), ajid I have 

 noted the existence of centrosomes in ciliated cells; and, on the 

 other hand, there are many cases in which they may be detected 

 in cells with two nuclei resulting from amitosis (Flemm ng, 

 Maximow) . 



My conclusions concerning the significance of mitosis and 

 amitosis in ciliated cells may be summarized as follows: 



1. The occurrence of amitosis in ciliated cells is not owing to 

 the lack of the centrosome; for the latter can be detected in many 

 cases in such cells. 



2. The sole method of multipUcation of cihated cells in inver- 

 tebrates is by mitosis, in vertebrates by amitosis; the cause 

 bringing about this difference between these subkingdoms, 

 must be due essentially to the degree of differentiation of the 

 cell-plasm. 



VII. DEVELOPxMENT OF CILIATED CELLS 

 A. HISTORICAL 



As early as 1875 Eichhorst described the development of cilia 

 in the ependyma cells of the spinal cord of man; a transparent 

 cuticle first appears at the distal border of the columnar cell; 

 this afterwards becomes striated longitudinally, the cilia passing 

 through this striated cuticle. According to Engelmann ('80), 

 cilia regenerate by the elongation of their rootlets, while Fol 

 ('96) described the formation of cilia by the prolongation of the 

 distal cell-border. Gurwitsch ('01) distinguishes two types of 

 cihogenesis: (1) first, the basal corpuscles appear at the nodes 

 of the alveolar meshes of the cuticle and afterwards the ciUa 

 become developed from them (in the oviduct of the rabbit and 



