1895.] MICROSCOPICAL JOURNAL. 10 L 



The Enterou of the Cayuga Lake Lamprey. 



BY AGNES M. CLAYPOLE, 



AKRON, OHIO. 



[Abstract.] 



The purpose of this investigation was to work out as 

 thoroughly as was possible the enteric structure of the 

 Cayuga Lake Lamprey, Petroinyzon dorsatus Wildnr. 

 With the exception of an article by S. H. Gage "On The 

 Lake and Brook Lampreys of New York" no special 

 studies have been made on the structure and metamor- 

 phosis of the North American Brook and Lake Lampreys. 



Material for this work was obtained during 10 months 

 of the year and many different hardening and staining 

 fluids were used. Owing to the three distinct natural 

 stages in the animal's life, the larval transforming and 

 adult forms were studied separately. 



The larval enteron was found to be a nearly straight 

 tube running the length of the body. The liver con- 

 tained, buried in its tissue, a large gall bladder from 

 which a duct led to the intestine. Alongside of the duct 

 ran the coeliac artery which entered the typhlosole of the 

 intestine. The portal vein arises on the outer walls of 

 the intestine at its caudal end and finally becoming free 

 enters the lower end of the liver. 



The tissue of the larval intestine is composed of a 

 muscular and a mucosal layer. The former has an outer 

 longitudinal and an inner transverse layer. The cells 

 had the usual appearance of unstriated muscular tissue. 

 Between this layer and the mucosa is a cavernous space 

 full of blood vessels. The mucosa is a single-celled 

 layer of epithelial cells, tall and columnar. Although 

 there are no groups of cells such are commonly called 

 glands, there is a differentiation of the epithelium for 

 purposes of absorption and secretion. There are groups 

 of ciliated cells at certain places but only at the cephalic 



