Oesophageal Valve 



63 



which it is secreted ; it is also closely applied to the 

 muscular layer. Like the generating epithelium, it is 

 thrown into longitudinal folds, which alternate with the 

 folds of the intima^. 



' 4. The muscles, circular and longitudinal. The cir- 



FiG. 47.- Diagram of oesophageal valve of Cluronomus-larva. A transverse 

 and a longitudinal section are here combined, the place of intersection being 

 marked by a thick line, m.ep, mesenteric epithelium, pm, peritrophic mem- 

 brane, in', reflected intima. st.ep', reflected stomodaeal epithelium. . 6.s, blood- 

 space, a.m, annular muscle-cells, step, stomodaeal epithelium, in, chitinous 

 intima. f.in, longitudinal folds of intima. 



cular muscles form the innermost layer, and are large 

 and conspicuous. At first they are simple, annular 



> Weismann has noted the presence of this chitinous layer in tlie 

 oesophagus of Muscidae, and in the stomach and intestine of Corethra. 



