599 



The preservation and stain are little short of perfect. Additional 

 material similarly treated includes epididymes of horse, opossum and 

 mule. Still other equally well-preserved material (Zenker's fixation; 

 haematoxylin and eosin stain) includes those of rat, bull, rabbit and 

 dog. The ciliated epithelium of the trachea of the cat, and of the 

 gills ot Unio, and the epithelium of the efferent tubules of the testis 

 of the lobster, is also included in the comparative study. 



Description. The epithelium lining the epididymis varies 

 according to the level of the section; proximally (vasa efferentia) 

 it consists of huge ciliated cuboidal cells (figs. 1 — 15), more distally 

 the cells are large columnar (figs. 16 — 43) carrying coarse cilia, 

 clumped in the nature of " brush borders" in the epididymis proper. 

 The cilia have apparently suffered considerable damage in manipu- 

 lation, especially in the efferent ductules. Moreover, they appear 



' '/ \ ■< 



All illustrations were drawn with camera lucida, and a B & L 1/12 oil im- 

 mersion lens witii number 10 ocular. 



Figs. 1 to 7. Portion of wall of epididymis (vas efferens) lined with cuboidal 

 ciliated epithelium. In 1 a cell membrane is forming between the intensely chro- 

 matic daughter nuclei. In cell 2 the division has begun on the lower surface of 

 the vesicular nucleus. In 3 amitosis is complete. In 4 the daughter nuclei are still 

 closely appresed. The nucleus of cell 5 is in resting condition, and stains deeply. In 

 6 division is complete, a cell membrane having formed; and the nucleus of the 

 daughter cell to the left is again undergoing amitosis. The division planes here 

 are vertical. In 7 division is beginning in a deeply chromatic nucleus in a horizontal 

 plane. Several of the cells show basal granules and terminal bare. 



to be somewhat more abundant on the columnar than on the cuboidal 

 cells. Both types have terminal bars and basal granules (figs. 2, 9, 

 17, and 40). 



The cuboidal cells are the more favorable for a study of the com- 

 plete amitotic process. Only here could the actual cytoplasmic fission 

 und the formation of new membranes be clearly observed. Cell 

 membranes are extremely delicate; in the regions lined by the co- 

 lumnar types, the cells are much more numerous per unit of area, 

 and so closely packed as to render distinction of cell boundaries fre- 



