362 The Microscope. 



lar. The longitudinal layer is described as originating from the 

 ridge on the dorsal face of the cricoid cartilage, and from the 

 inferior constrictor of the pharynx, while the circular layer comes 

 from the inferior constrictor of the pharynx alone. 



From Gillette (7),* we find that these layers are not as regular 

 as would be inferred from the descriptions. In the pharyngeal part 

 of the oesophagus, the longitudinal layer is thinner and more 

 uniform than in the gastric part, where it is somewhat separated 

 into bundles, and of these "some are parallel, some inter-cross, 

 some divide and anastomose with each other. This inter-crossing 

 and anastomosing takes place not only superficially, but also below 

 the surface ; that is to say, the ectal fibres become ental, and vice 

 versa. In certain places a complete and almost inextricable 

 entanglement is found." 



With respect to the circular layer, the same author says that 

 the fibres are not arranged in a regular manner. " There are 

 complete and incomplete rings, sometimes inter-crossing at a more 

 or less acute angle, and enclosing between them fibres that connect 

 one ring with another." 



The veterinary anatomists, presumably following the human 

 anatomists, for a long time described a similar arrangement of the 

 oesophageal muscles in the domestic animals. Gerardus Blasius (2) 

 in 1681 described the arrangement of the muscle fibres in the 

 tesophagus of the dog as follows: "The fibres are divided into 

 two spirals, which meet in definite places, on the anterior and 

 posterior walls, and intersect each other so that one goes under 

 the other. They intersect by turn, so that the right seeks the 

 left and the left the right. What constituted the external tunic 

 becomes the internal, and again the external." 



This arrangement, described by Blasius, is not found mentioned 

 by any other author. 



Leyh (12), in 1859, said that there were two muscular coats of 

 the oesophagus: an external longitudinal, and an internal circular. 

 He did not mention any difference as existing between the horse 

 and the ox. 



Strangeway (17), 1870, also divided the muscular coat into 

 two layers, the external being composed of longitudinal fibres, and 

 the inner of " spiral or circular " fibres. 



Chauveau (3), in 1872, makes it evident that these coats are not 



* The number in parenthesis following an author's name refers to the bibliography at 

 the end of this paper. 



