of the Fishery Board for Scotland. 



43 



Fig. 15. — Optical longitudinal section of a 4| days embryo, showing the 

 blastopore shortly before closing. 



Fig. 16. — Optical transverse section about the same stage. 



Fig. 17. — Optical section of the longitudinal axis of an embryo at the end of 

 the 4th day, showing the closure of the blastopore and the space between the 

 cells in the thickened rim, which are derived from the archiblast and those 

 supplied by the parablast. 



Fig. 18. — Later stage not described in this paper but which is given here for 

 reference. 



Fig. 19. — Section of an unfertilised ovum stained with carmine. The yolk 

 is unstained and the germinal protoplasm shows as a network between the 

 yolk spheres. 



Fig. 20. — Section of an ovum 4 hours after fertilisation, showing the 

 collection of protoplasm into the germinal mound and the processes which are 

 still left in communication with the yolk. The yolk spheres are not indicated 

 in outline. 



Fig. 21. Diagrammatic section of a blastoderm at the commencement of the 

 pseudo-invagination process. The shading in the marginal rim shows the cells 

 derived from the parablast. 



Fig. 22. — Diagrammatic transverse section of a stage similar to that shown in 

 fig. 12, showing the keel (axis of the embryo) and lateral prolongations of the 

 blastoderm, which are thickened at the margin. 



Fig. 23.— Diagram showing the formation of the primitive hypoblast from 

 the parablast. 



Fig. 24. — Section of an embryo (somewhat diagrammatic) about 4^ days old, 

 showing the three primary germinal layers. In reality the blastopore is 

 closed at this stage. 



ARE HERRING OYA LIKELY TO DEVELOP J^OEMALLY ON 

 THE DEEP OFFSHORE FISHING BANKS ? By J. C. Ewart, 

 M.D., Regius Professor of Natural History, University of Edinburgh, 

 Member of the Fishery Board for Scotland. 



Until comparatively recent years nearly all the herring taken in 

 summer were captured by small boats within a few miles from the shore. 

 In 1852, e.g., immense herring shoals reached the Moray Firth to spawn 

 on the Guillam and other inshore banks. Since 1852 the fishing boats 

 have greatly increased in size, and owing to the introduction of cotton 

 nets, each boat has added greatly to its catching power. 



As the boats have increased in size and sea-worthiness, the fishermen 

 have proceeded farther and farther to sea in search of the herring shoals, 

 and now the greater number of the herring are taken from 40 to 60 miles 

 from the coast. It is often alleged that it was owing to the herring 

 deserting the inshore grounds that the fishermen proceeded to sea in 

 search of the shoals, and also that it is because the fishermen disturb and 

 break up the shoals early in the season that they no longer or seldom 

 visit their old spawning grounds. There is no doubt that during the last 

 fifteen years comparatively few herring have been captured during the 

 summer over the inshore banks of the Moray Firth ; but whether this is 

 the result (as is alleged) of the fishermen intercepting and breaking up 

 the shoals before they have had time to reach the inshore ground it is 

 impossible to say. It is, however, a question of great interest, and one 

 which could in all probability be easily settled. There is in German 3% 

 Russia, Poland, and other continental states, a considerable demand for 

 large full cured herring. For some years our curers have been attempting 

 to meet this demand by sending large parcels of small fish with the milts 

 and roes in many cases only partially developed. 



