of the Fishery Board for Scotland. 1*1*7 



tank was increased, but it was judged that that would not suffice, and the 

 blackened parts of the spawn were torn off, the portions that seemed in 

 good condition being replaced in their old position. The spell, however, 

 was broken. The male did not resume his attention to the eggs, the mass 

 of which was indeed much broken up and diminished in size. He pushed 

 some of the pieces about the tank and withdrew. Both he and the eggs 

 were placed in another tank, without any better result. He pushed the 

 pieces about a little and left them. And when the other male was 

 introduced, he seemed oblivious to its presence ; his animosity, at first 

 associated no doubt with reproduction and fertilisation, and then with the 

 care of the eggs, had quite departed. 



On examining the portions of the egg masses that remained, the surface 

 was found to be flocculent from the empty egg-shells from which the 

 young fishes had escaped, most of which were still attached to it. On 

 the other hand, the interior of the mass was solid, the eggs all containing 

 embryos, some of which had died, but many Avere subsequently hatched 

 out in jars. From an early pericd some of the eggs, but not many, next 

 the glass in front of the tank, were observed to be white and opaque 

 (dead), but they did not decay. 



The difficulty of hatching the eggs of the lutnpsucker was pointed out 

 previously by M'Intosh, who stated that in tanks they speedily acquire a 

 fetid odour, that the death of a few causes putrefaction of the whole, and 

 that they had not yet been hatched out in tanks.* He does not give any 

 particulars as to the dimensions of the tanks or the flow of water, but 

 probably the chief difference between his experiments and that described 

 here was that the male in the latter case was constantly engaged in tending 

 the eggs, which shows how efficient that attention may be. 



The hatching of the eggs, so far as it was accomplished in the tank 

 under the care of the male, extended from the 5th to the 22nd of May, 

 or seventeen days. The greater number were still uuhatched on the 

 latter date. It seems a long period, considering that the eggs were 

 deposited, and no doubt fertilised, at practically the same time. Under 

 natural circumstances, it is probable that the time taken for the hatching 

 of all the eggs is prolonged, for it is difficult to understand how the larvae 

 could make their way from the interior of the mass by the narrow channels 

 between the eggs if the eggs there were hatched as soon as those on the 

 exterior. The condition of the masses shows that this does not occur, and 

 that hatching proceeds from the outer surface inwards, a process which must 

 take a considerable time. It seems very likely that the development of the 

 eggs towards the centre of the mass is retarded, owing to defective or 

 inferior aeration there, compared with the eggs on the surface and near it ; 

 and that this is related to the gradual disintegration of the outer surface 

 as the eggs hatch there, and a pathway of escape is opened to the larvae. 



One could not fail to be impressed with the advantage to the species 

 of this guardianship of the eggs by the male fish. Numerous foes must 

 be driven off and the eggs preserved, and I do not think the story of 

 Fabricius, that the lumpsucker under such circumstances will attack the 

 wolf-fish, need be doubted. The courage and pugnacity of this usually 

 docile and inoffensive fish seem boundless when it is protecting its eggs, 

 and in contests of this kind it not infrequently happens that courage and 

 determination count for as much as strength and the power of inflicting 

 real injury. 



The conclusions from the experiment may be thus summarised : — 

 (1) The male alone defends the eggs, the female taking no part 

 whatever in protecting them. 



* Annual Reports Fishery Board for Scotland, 3rd, p. 60 ; 14th, p. 272. 



M 



