402 MAINE) AGRICUI.TURAL IjXPKRIMEjNT STATION, I912. 



what diagonal!)^ with respect to the long axis of the oviduct. 

 A Httle farther down the duct the fibers in this layer run around 

 the oviduct at right angles to its long axis, i. e., become circular 

 muscles.* 



The innermost layer of the oviduct is the epithelium. From 

 it arise all the glands which have to do with the secretion of the 

 various egg substances. 



In its embryological development, this epithelial layer has an 

 origin very different from the other layers of the oviduct. The 

 Anlage of the oviduct, known as the Miillerian duct, arises as a 

 thickening along the Wolffian body just ventral to the gonad. 

 This Miillerian duct is at first a solid cord of cells. It later 

 acquires a lumen and grows posteriorly until it connects with 

 the cloaca. At the time of this posterior growth mesenchyme 

 cells migrate in from the surrounding tissue and form a layer 

 about the duct. From this layer of mesenchyme cells are devel- 

 oped all the outer layers of the oviduct i. e. the muscles and 

 connective tissue. On the other hand the epithelium and its 

 derivatives, i. e., all glandular structures, are formed from the 

 walls of the old Miillerian duct. Corresponding to this differ- 

 ence in origin, the functions of the two sets of tissue are entirely 

 different. The epithelium is entirely concerned with secretion 

 and ciliary movement while, as would be expected, the deriva- 

 tives of the mesenchyme are concerned with supporting and 

 muscular functions. 



We will defer the description of the minute anatomy of the 

 epithelium until we have examined the general relation of the 

 layers in other parts of the funnel region. 



Figure 458 shows under low magnification a section from 

 near the middle of the funnel. (Cf. fig. 453). The wall of the 

 oviduct is of about the same thickness here as near the funnel 

 mouth. (Fig. 457) The same layers of tissue are present as 

 in figure 457, but the muscles are arranged in more definite 

 layers. The most marked difference in the two sections is in 

 the height and arrangement of the longitudinal ridges. It is 

 clear that these ridges are very much better developed in the 

 middle of the funnel than nearer the mouth. These longitudinal 



* It is of importance to mention here that Sacchi says that the outer 

 layer of muscles is circular and the inner layer longitudinal. This is 

 certainly an error. The point will be discussed more thoroughly in a 

 later section of this paper. 



