112 JESSE LE ROY CONEL 



seen in the center of the lumen of the duct throughout its entire 

 length. Toward the distal ends of the cells are numerous small 

 and large, yellowish, round or oval bodies of homogeneous struc- 

 ture, which resemble oil droplets. Some of these are minute 

 granules, while others are as large as the nucleus of the cell. 

 They are especially numerous and large in the cells on top of the 

 ridges, and are distributed in no definite manner. Only a few 

 are found in the cells between ridges. These bodies are prob- 

 ably what Yl. Miiller described as yellowish pigment granules. 

 The largier bodies do not resemble pigment granules, however. 



The long, columnar cells are always arranged on the ridges 

 in the shape of a fan, as illustrated in figure 53. To form a 

 ridge, the entire layer of epithelial cells bends into the lumen of 

 the duct, and the connective tissue outside the basal membrane 

 of the epithelium makes a core which fills the concavity beneath 

 each ridge (fig. 53). 



The ridges are more numerous in the adult male ducts than in 

 the adult female. They are also higher, but the cells are no 

 longer than those of the female. The greater height is due to 

 the fact that the epithelial layer extends farther into the lumen 

 of the duct in the males. Wide ridges are more numerous in 

 the male than in the female, some of them being flat on top. 

 The concavities formed by the infoldings of the epithehal layers 

 are larger in the male than in the female, and are also filled by a 

 core of connective tissue. 



Maas ('97) has suggested that the mesonephric ducts are not 

 simply excretory, but they may have a secretory function as 

 well. The distribution of the blood vessels, the presence of ciha, 

 the folded epithelium, the enlarged condition of the ducts in 

 comparison to the small tubules of the Malpighian bodies of the 

 mesonephros have been mentioned in the literature as indicative 

 of such a possibihty. The many large foldings or ridges of epi- 

 thelium certainly increase the epithelial surface far beyond what 

 would seem necessary for excretion alone. The enlarged, con- 

 voluted condition of the ducts in the males is very peculiar. 

 The presence of the small and very large, yellowish bodies near 



