THE STURHEONS AND STURGEON INDUSTRIES- 
253 
The outgoing passages from the abdominal cavity are.somewhat difficult to under- 
stand without reference to Figs. 51 and 52, to which the reader’s attention is directed 
in the accompanying Plate LVIII. The oviducts of the sturgeon (Muller’s ducts) open 
into the abdominal cavity by capacious funnel-shaped mouths on either side of the air- 
bladder. They open forward and are so spacious at their anterior extremities that 
the whole hand may readily be thrust into them at that point in the adult fish. They 
gradually narrow in their backward course and extend for a few inches only as sepa- 
rate canals which overlie the more deeply embedded urinary passages into which they 
open at their posterior terminations. After the oviducts open into the urinary pas- 
sages, from that point backwards the latter become properly entitled to the designation 
of genito urinary, since they then form a common outlet for the escape of the renal 
secretion from the Wolffian body as well as the generating products set free by the 
ovary. The common genito urinary passages of either side are then continued back- 
wards till they become confluent near the vent, just behind which they open to the 
exterior. 
In the male the arrangement appears to be somewhat different. The spermatic 
ducts from each testis open directly into the urinary duct (segmental or Wolffian 
duct), though the oviducts are also well developed in the male and not at all rudiment- 
ary as in the males of higher animals. The spermatic secretion or milt does not 
therefore pass out of the testes by way of the oviducts, but takes a more direct course 
into the urinary duct (Wolffian), which extends in both sexes much farther forward 
than the oviduct. The urinary passages, which are as spacious in the male as in the 
female, therefore become, for a greater portion of their length than in the latter, 
efferent genito-urinary outlets. 
The mesonephros, Wolffian body, or permanent kidney of the sturgeon, discharges 
its secretion into the primitive segmental or Wolffian duct, which widens as it passes 
backward just before it receives the oviduct which joins it. Upon slitting open the 
widened posterior portion of the urinary or segmental duct the mouths of the col- 
lecting ducts of the segmental tubules of the kidney are exposed, and are seen to be 
scattered over its dorsal wall, showing that the renal secretion is poured out directly 
into it. There is no dilatation of the posterior portion of the segmental duct into a 
urinary vesicle or bladder as occurs in many Teleosts. 
The posterior portion of the mesonephros of the sturgeon is most strongly devel- 
oped; and in this region it lies just internal to the segmental ducts as a flattened and 
widened series of renal lobules composed of closely agglomerated uriniferous tubules 
and Malpighian glomeruli. In the region of the air-bladder, and overlying it on 
either side of the vertebral column, the renal lobules become suddenly much smaller 
in the young, while in front of it they again increase in size. How much of the pro 
nephros or head kidney persists is not known, nor has it been determined in just 
what way the secretion from the anterior part of the mesonephros reaches the seg- 
mental ducts. The proportions of the glandular portions of the renal apparatus at 
different points of its extent is shown in Fig. 51, Plate LVIII, showing the dorsal wall 
of the body cavity as viewed from below. 
The foregoing account of the viscera of the sturgeon deals in the main with 
the naked-eye appearance of its parts. 
