of the Fishery Board for Scotland. 



31 



APPENDIX R— No. I. 



ON THE DEVELOPMENT OF THE HERRING. Part 11. By 

 George Brook, F.L.S., Lecturer on Comparative Embryology in 

 the University of Edinburgh. (Plates I. and II.) 



The Early Stages of Development. 



The egg of the herring is one which offers several advantages to the 

 student of fish development. Not the least of these is derived from the 

 fact that the germinal disc is only formed after fertilisation, so that it 

 may actually be Avatched in process of formation. The conclusions which 

 I have been led to regarding the development of the herring are, generally 

 speaking, in harmony with those of Kupffer. That investigator had not, 

 however, the advantage of studying a complete series of sections of the 

 ova ; and where my observations differ in any important degree from his, 

 the difference is, I think, mainly to be attributed to this fact. 



A detailed account of my observations, and of the theoretical con- 

 siderations suggested by them, has been brought before the Royal Society 

 of Edinburgh. It will therefore only be necessary to give here a short 

 account of the experiments conducted in connection with the fertilisation 

 of the eggs and of the additional information which has been obtained by 

 a renewed study of the development of this most important food fish. 



My thanks are due to the directors of the Rothesay Aquarium for the 

 readiness with which they placed their establishment at my service for 

 these experiments, and to their manager (Mr Shields) for the valuable 

 assistance which he rendered. 



1. Experimental Work. 



For the purposes of my investigations a considerable number of ripe 

 herring were obtained from the Ballantrae Banks in March last, and con- 

 veyed alive to Rothesay on board H.M.S. 'Jackal.' The herring were 

 then safely transferred to the tanks of the Rothesay Aquarium for further 

 study. The fish were 'under observation for a month, but gradually 

 died off, as they were unable to withstand the rough usage and handling 

 necessitated by the experiments. 



Of eight different batches of eggs that were under observation, seven 

 were fertilised artificially, and the eighth was shed by the fish in transit. 

 As Professor Ewart has already pointed out, there is little difficulty in 

 fertilising the ova of the herring artificially, and my recent experiments 

 in this respect were very satisfactory. There appears no reason why this 

 could not be accomplished on a large scale. 



Previous authors are not agreed as to the action which the sper- 

 matozoon has on the ripe ovum. Kupffer (1), after repeated experiments, 

 concludes : — 



1. That the herring ovum shows at the moment it reaches the water 

 from the oviduct no trace of a germinal disc, or indeed any separation 

 into formative and nutritive yolk. 



2. That water per se alters nothing in the relations of the yolk, nor 

 of the egg membrane with the yolk. No water enters through the egg 

 membrane, nor does the latter separate from the yolk after immersion in 

 water for twenty-four hours. 



3. If, however, the water in which the eggs are deposited is previously 

 supplied with milt, or if the milt is added some hours after the eggs have 



