30 



Part III. — Twenty-seventh Annual Report 



S. Spr.— 18 to 28 cm. : eggs, 3--8, 1-0 mm. : o, 4-22 mm.: t, 6-25 mm. : 

 fat, "great quantity" to 'practically none." 



Unclassified, 19 to 28 cm.: eggs, -\-'25 mm.: o, 2-8 mm.: t, 4-12 

 mm. : fat, "great quantity" to "some." 



Summer Spents. — The summer spents of last year are becomiEg summer 

 spawners. The fishes which have been diagnosed as summer spents were 

 slack in the belly; the reproductive organ showed "spent" characters, 

 although the eggs were developing. There was generally a large quantity 

 of abdominal fat present. The ovary was reddish in colour, plump, filled, 

 but soft. The ridges were filled with eggs, some of which were storing up 

 yolk, while the majority remained smaller and clear. When the ovarian 

 tissue is teazed the very small yolked eggs can be detected as white grains 

 in the tissue. They can be recognised by the naked eye when -27 mm. in 

 diameter, though sometimes, although bigger, they may not be satisfactorily 

 made out. In two summer spawners, 23 and 24 cm. long, having eggs 

 •3 mm. in diameter, old follicles were detected, an indication of the fishes 

 having spawned before. 



The testis is pink in colour, and has a thin edge. When teazed out and 

 washed in water a shreddy honeycomb structure can be made out. 



Winter Spents. — There is difficulty in separating the summer spents of 

 last year from the winter spents of the present year. Possibly some of 

 those which appear to be advanced winter spents may belong to the former 

 class. In June few herrings below 20 and 21 cm. in length should be 

 winter spents, because, although they spawn when under that size, they 

 should by that time have probably reached that size. The summer spent 

 is simply a certain distance ahead of the winter spent in its ripening. The 

 summer spent might occupy the position of the more precocious winter spents. 



The rule I have followed has been to regard those having eggs *3 mm. 

 and over in diameter as summer spawners, more especially if the other 

 fishes in the series showed reproductive organs farther advanced than that ; 

 while if the majority of the sample had eggs smaller than '3 mm., with a few 

 reaching that size, then I have regarded the lot as winter spent. The two 

 classes will probably overlap and mix. The late summer spents and the 

 early winter spents will, one expects, spawn at the same time, probably as 

 autumn spawners. 



The condition in which the reproductive organ is a flat, red, dry skin, is 

 apparently a resting stage, during which the fish grows in length and stores 

 up abdominal fat. Some fishes had clear crystalline concretions in the 

 ovaries : they appeared to be in some cases old eggs. But clear concretions 

 were also found in some very small testes. Budding was apparently taking 

 place in some ovaries. When a piece of an ovary is crushed on a slide 

 beneath a cover glass old follicles are sometimes to be seen in a dark roll 

 shape, occasionally semi-circular in form, surrounding a young egg. 



The testis of the winter spent was pink in colour, narrow, shrunken, 

 with sometimes a thin edge, and a shreddy honeycomb structure filled with 

 coagulable albuminous fluid. In some the remains of pouches can be made 

 out. The elastic honeycomb sponge structure is getting filled up. The 

 testis is sometimes a flattened skin. There are crystalline concretions in 

 the testis. Might the unspawned milt assume this form ? 



There are apparently several distinct stages in the spent reproductive 

 organ. Immediately after spawning it is a loose, flabby, skin-like bag. It 

 gradually shrinks while the new crop of eggs is being formed. It may 

 become a narrow, flattened, thin, dry skin, containing the new crop of eggs. 

 Old follicles were made out in ovaries of this character. When the ovary 

 begins to develop it swells out, is soft, and is roomy inside. The soft, 

 clinging nature of the stroma is characteristic of this stage. Eggs 2 mm. 

 in diameter were found in one of these ovaries. The eggs were fairly 

 uniform in size. The ovarv mav be red in colour, and narrow. In a 



