134 PROF. HUXLEY ON THE OVIDUCTS OF OSMERUS. [Mar. 20, 



As might be expected, I have found Rathke's statements, so far as 

 the matters of fact are concerned, perfectly accurate. 



Between the latter part of January and the beginning of March of 

 this year I have examined a number of female Smelts, and always 

 with the same results. I may remark that the ovaries were fully 

 developed in the former month, and that, in the first week of March, 

 four Smelts which 1 obtained in very fresh condition were all females, 

 full of detached ova and ready to spawn. 



The abdominal cavity of a female Smelt, in this state, is distended 

 by a mass of ova, which are closely compacted and coherent, but 

 become readily detached from one another when the mass is gently 

 agitated in water or other fluid. 



When the abdominal wall of the fish is carefully slit open along 

 the ventral median line, the mass of impacted ova has almost the ap- 

 pearai:ce of a vast single ovary ; and, indeed, Bloch appears to have 

 been misled by this appearance (Rathke, I. c. p. 132). But it may 

 be readily broken up and washed away ; and the two ovaries are then 

 seen, one on each side of the middle line— not opposite one another, 

 however, but the left in the anterior, and the right in the posterior 

 half of the abdoaaual cavity ' (fig. 1, j). 135). Each ovary has the form 

 of a half-oval plate, with the curved edge ventnJ and the straight edge 

 dorsal. The latter is suspended by a narrow mesoarial fold of peri- 

 toneum from that pi.rt, of the dorsal wall of the abdominal cavity 

 which corresponds with tlie ventral face of the air-bladder. The 

 line of attachment of the mesoarium is parallel with that of the 

 mesentery and a little distance from it. 



What may be termed the body of the ovary- is a broad and thin 

 plate, and its inner face is covered by peritoneum. The ovarian 

 artery enters the left ovary at its anterior internal angle, and then 

 passes backwards along the middle of its inner face, giving off 

 branches as it goes. The artery of the right ovary runs from behind 

 along its dorsal edge, and then passes obliquely across its inner face 

 forwards. The outer face of the body of the ovary gives rise to a 

 great number of ovigerous lamellce of a broadly triangular form, 

 which are disposed transversely to the length of the organ and per- 

 pendicularly to its body (fig. 1, B, C). 



In fish which are not ready to spawn, these ovigerous lamellae are 

 very thick, from the number of close-set ovisacs with which they are 

 laden, and the clefts which separate them are extremely irregular. 

 In those in which the abdominal cavity is full of eggs, the lamellae 

 from which the eggs have been discharged remain as thin plates 

 separated by tolerably regular interspaces as wide as, or wider than, 

 the thickness of each plate. The outer face of the ovary is not 

 wholly occupied by the ovigerous lamellae. On tlie contrary, the 

 peritoneal layer of the inner face is continued over the ventral edge 

 of the ovary, and ends at about a third or a fourth of the height of 

 the outer face by a well-defined margin. Hence the outer face of 

 the ovary appears transversely laminated only above and in the 



' Conf. Eatbke, I. c. p. 135. 



2 Cmif. Eatbke, I. c. pp. 121 & 175. 



