1884.] Artificial Fertilisation of Herring Ova, 457 



being in a straight line with the trunk and the pectoral fins near or 

 resting on the bottom. While in this position, a thin beaded ribbon 

 was seen to escape from the genital aperture and fall in graceful 

 curves, so as to form a slightly conical mass, almost identical with 

 a cluster of ova on one of the stones dredged at Ballantrae. As 

 the little heap of eggs increased, some falling to the left side one 

 moment, while others fell to the right the next, according to the 

 currents in the water, the males continued circling round the 

 spawning female at various distances, while the other females in the 

 tank remained apart. The males kept from 8 to 10 inches above the 

 bottom of the tank and formed circles ranging from 18 inches to 

 30 inches in diameter. Some of the males were swimming from right 

 to left, others from left to right, and although there was no darting 

 about, no struggling among themselves (there is nothing about the 

 structure of the herring that suggests struggling), no great excite- 

 ment, there was a peculiar jerking of the tail as they performed their 

 revolutions. Soon the object of this peculiar movement was suffi- 

 ciently evident. Three or four times during each revolution each fish 

 expelled a small white ribbon of milt, which varied from half an inch 

 to three-quarters of an inch in length and was nearly a line in breadth 

 across the centre, but pointed at both ends, and somewhat thinner 

 than it was broad. The delicate ribbons slowly fell through the water, 

 sometimes reaching the bottom almost undiminished in size, but in 

 most instances they had almost completely dispersed before reaching 

 the bottom. In this way the whole of the water about the female 

 became of a very faint milky colour, and practically every drop of it 

 was charged with sperms, as was afterwards ascertained. It will thus 

 be seen that there is no attempt whatever on the part of the males to 

 fertilise the eggs as they escape from the female. While the female 

 is depositing eggs at the bottom the males concern themselves with 

 fertilising the water in the neighbourhood, and it will be observed 

 that the males are careful to guard against the influence of currents. 

 By forming circles around the female, and shedding milt on the way, 

 it matters not how the currents are running, they are sure to carry 

 some of the milt towards the eggs — the milt, like the eggs, sinking 

 though not adhering to the bottom. 



This, then, is the natural process of depositing and fertilising the 

 ova of the herring in comparatively still water. I watched the 

 whole process repeatedly, and the details were always the same. 

 When the female had deposited a certain number of eggs at any 

 given spot, she moved forward in a somewhat jerky fashion without 

 rising from the bottom, and as she changed her position the males 

 changed theirs, so that the female was always surrounded by a fine 

 rain of short sperm ribbons. A specimen of hydrallmannia, sent from 

 Eyemouth, seems to indicate that the female moves about amongst 



