108 FRANK HELVESTINE, JR. 



only a narrow layer of cytoplasm. In regard to this epithelium, 

 Peck gives no further details. 



Henneguy2 and v. Lenhossek,^ working independently, ex- 

 pressed at about the same time (1898) their opinion regarding 

 the origin of cilia, and especially the basal granules. The Len- 

 hossek-Henneguy hypothesis states that the basal bodies of 

 ciliated cells are identical with the centrosome, that is, derived 

 from it, and it is based on, 1) a series of histologic analogies 

 between the basal bodies and the centrosome and, 2) histologic 

 details that seem significant. 



A comparison between the centrosome and the basal corpuscles 

 brings out the following facts: a) both bodies have the same 

 form; h) they stain alike and with the same intensity; c) in 

 unstained preparations the basal bodies refract light to the same 

 degree as does the centrosome and, d) the position of the centro- 

 some in certain non-ciliated cells corresponds to the position 

 of the basal corpuscles in adjacent ciliated cells. The evidence 

 furnished by certain workers* seems to lend weight to the hypoth- 

 esis: a) ciliated cells have no centrosome; b) certain ciliated cells 

 do not divide by mitosis, and, c) ciliated cells resemble the 

 spermatozoon, the flagellum of which is derived from the cen- 

 trosome. 



In 1913 Jordan^ showed that amitosis is the exclusive method 

 of division in the ciliated cells of the vasa efferentia of the white 

 mouse. That amitosis is the general mode of division in ciliated 

 cells was supported by observations on the epididymis of the 

 rat, horse, bull, mule, rabbit, and dog and the trachea of the cat 

 and the ciliated cells of the gill of Unio. On the basis of his 

 results Jordan suggested that the fundamental cause of amitotic 

 division in the ciliated cells is the destruction of the centrosome 

 in the formation of basal bodies from which the cilia develop. 



Saguchi"^ more recently ('17) has made an extensive compara- 

 tive study of ciliated epithelium from various regions in a num- 

 ber of both invertebrate and vertebrate forms. He claims to be 

 able to detect centrosomes in ciliated cells of both invertebrates 



* The literature pro and con has recently been very fully reviewed by 

 Saguchi.^ 



