THE STUEGEONS AND STURGEON INDUSTRIES. 
249 
shows that the cells of this tissue are active here, as iu other forms, in taking up the 
nutriment from tbe food which passes through the alimentary tract. The mucous 
membrane of the spiral valve is covered with villi, which are as well developed over the 
sides and edge of the spiral fold as upon the proper walls of the intestine of this 
region. The relations of the parts described are well shown in a cross-section of the 
region of spiral valve represented in Fig. 47. 
The mesentery which suspends the hind gut, or spiral valve, to the dorso-median 
line of the body-cavity is entire, and six or seven blood-vascular branches are given 
off from the posterior mesenteric artery which take the curved spiral direction of the 
spiral valve after they reach and traverse the wall of the intestine. The mesentery of 
the hind gut is nearly one-fourth of an inch wide in a young fish 9 inches long. Farther 
forward at the V-shaped loop formed by the duodenum and small intestine together, 
the mesentery is much wider, and at the apex of the loop is perforate, and in this 
widened part of the mesentery of the last loop the spleen is embedded as a V-shaped 
glandular mass, having the same general curvature as the intestinal loop itself. The 
histological structure of this organ leaves no douot of its spleen-like nature. 
Still farther forward the dorsal median mesentery becomes narrower, so that the 
alimentary canal comes to lie in immediate contact with the dorsal wall of the abdom- 
inal cavity. Below, the median anterior ventral mesentery gives passage to the por- 
tal vessels from the liver, which pass to the auricular end of the heart. The Cuvier- 
ian ducts pass downward through the pericardium on either side of the oesophagus to 
join the venous end of the heart, thus collecting all the blood from the systematic cir- 
culation to retnrn it to the heart. This is s})oken of here since the pericardium, on its 
posterior face, is continnous with the serous lining of the body-cavity and the ante- 
rior median mesentery. 
The liver is the largest glandular viscus of the young sturgeon, and it is lighter 
colored than in the adult. Its right lobe is considerably larger than the left, and both 
lobes have their thin posterior and inferior margins reflected over the pyloric end of 
the stomach. The gall-bladder lies in a fossa, or depression, on the median face of the 
right lobe, and between the latter and the thick-walled pylo ric end of the stomach. 
The anterior portions of both the right and left lobes of the liver are so conformed 
to the shape ot the anterior part of the body-cavity as to fit with great nicety to the 
configuration of the lateral walls of the abdomen and pericardium in this region. 
The histological structnre of the liver of the sturgeon has not been investigated 
by the writer, as it has not been the purpose to deal with especial minuteness with 
organs the functions and character of which are well known. The minute structure 
of the“ pancreas” (so called by Weidersheim, Lehrbuch der Vergleichendeu Anatomic, 
second edition, 1886, pp. 533-535), but correctly identified as the milt, or spleen, by 
Brandt and Ratzeburg (Mediziuische Zoologie, 1833), is of more interest, since it dis- 
plays the typical structure of spleen in a very simple form. In a matrix of lymphoid 
tissue, lymphoid nodules, or masses, very irregular in form, are embedded and trav- 
ersed by blood-vessels. In sections of the organ, before staining and clearing is 
resorted to, very characteristic globular cells are found embedded in the lymphoid 
nodules of the organ ; these cells are uniformly granular, opaque, and quite unlike the 
rest of the cells of the organ, and about three times as large as the usual type of cells 
which form the greatest proportion of the spleen pulp. They are very numerous iu 
some of the lymphoid nodules, less so in others; the granules which they contain are 
