April I, 1884] 



NA TURE 



539 



to stones, seaweed, and sea-firs. The>e stones coated with egsjs 

 varied from 6 inches t > I J inches in length, and from 4 inches to 

 1 inch in breadth, but in all cases the eggs were attached to a 

 comparatively smooth surface, and they were arranged either in 

 losir cones or in comparaiively thin layers one or two eggs deep. 

 The eggs on the sea-tirs were always attached in small clusters 

 about half an inch in diameter around the stems. On examining the 

 spawn found on the stones and seaweed, embryos at various stages 

 of development were at once visible, some of them apparently 

 only three days old, while others had distinct eyes, and froai 

 their violent movements and their size seemed almost ready for 

 hatching. Some of the egg-cmted stones we.e taken to the 

 University of Edinburgh, where the eggs hatched on March 15, 

 eight days after their removal from the spawning ground, and to- 

 day (March 17) they are three-eighths of an inch in length, 

 extremely active, and swimming freely about in the water. 



By taking soundings over the Ballantrae Bank in various 

 directions, it was ascertained that it c msisted of rock, stones, 

 shells, and coarse sand, anl that the depths varied from 7 to 13 

 fathomi. The outer edge of the bank shelved at most paints 

 rapidly until a depth of 17 fathoms w.is reached, and at this 

 depth the bottom consisted of fine, soft mud. While on the 

 east coast spawning grounds e.\amiiied during the autumn tlie 

 surface temperature in most cases varied from 53° F. to 55' F., 

 and the bottom temperature from 52' F. to 54° F., even at a 

 depth of 40 fathoais, the temperature at the Ballantrae Bank 

 varied from 42°'S to 43''8 F. at the surface, and from 43"5 

 to 42"'8 F. at the bottom. The corres^ionding surface tempera- 

 ture, however, on the ea-t coast during the week ending March 8 

 was from 2° to 3° F. lower than at Ballantrae. 



According to previous observers — 



" When spawning takes place naturally, the eggs fall to the 

 bottom and attach themselves." " But at this time the assembled 

 fish dart wildly about and the water becomes cloudy with the 

 shed fluid of the milt. The eggs thus become fecundated as they 

 fall, and the development of the young withia the ova sticking to 

 the bottom commences at once." 



Mr. Mitchell, in his book on " The Herring," referring to the 

 once famous spawning bed off Dunbar, states that — 



" About August }iO the shoals began to deposit their spawn a 

 short distance from the harbour, and on September 3 the fisher- 

 men found that a very large body of herrings remained fixed to 

 the ground in the progress of spawning, the ground being of a 

 rocky or stony nature." 



While many fishermen believe that herring spawn on hard 

 ground, some believe that they also spawn on a clayey 

 bottom ; and while some think they spawn near the bottom, 

 others affirm that they spawn near the surface. Having 

 secured at Ballantrae a large number of live herring, so ne 

 of the largest and ripest males and females were placed in 

 a large wooden tank into which a number of stones an 1 a qu mtity 

 of seaweed had been previously introduced. After the fish had 

 been about two hours in tiiis tank, the stones and seaweed were 

 examined. Although a few e^gs were attached to both stones 

 and seaweed, it was qaite evident that the eggs had not been 

 deposited in the same way as those found on the stones dredged 

 on the previous day ; but we were not surprised that only a few 

 isolated eggs were found on the stones, bicaue the fish had been 

 disturbed every few minutes by the pouring of water into the 

 tank. 



On reaching Rothesay the hatching boxes and live herring 

 were at once transferred from H.M.S.ya-'^a/to the tanks — a tank 

 into which comparatively little light entered being selected for 

 the ri.iest and mist vigorous herring. In about half an hour 

 after they were introduced a large full herring was seen moving 

 .si )vvly about the bottom of the tank with f jur other fish making 

 circles around her at some distance from the bottom. Appeiring 

 satisfied with a particular stone which she had evidently been 

 examining, she halted over it and remained stationary' for a few 

 minuses about half an inch from its surface, the tail being in a 

 straight line with the tank 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 opening and fall in graceful curves on the surface 

 of the stone, so as to form a slightly conical mass almost identi- 

 cal with a cluster on one of the stones dredged at Ballantrae. 

 As this little heap of e^gs increased — some falling to the leftside 

 one moment, while others fell to the right the ne.\t, accjrding to 

 the currents in the water — the miles continued circling round 

 her at various di-tances, while the other females in the tank 



remained apart. The males remained from 8 to 10 inches above 

 the bottom of the tank, and formed circles varying from 18 

 inches to 2 feet 6 inches in diameter. Some of the males were 

 swimming fro ji right to left, others from left to right ; and although 

 there was no dartmg about, no struggling amongst themselves, 

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

 revolutions. Soon the object of this peculiar movement was 

 sufficiently evident. Three or four times during each revolution 

 each fish expelled a small white ribbon of milt, whi.h 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. These delicate 

 ribbons slowly fell through the water, sometimes reaching the 

 bottom almost undiminished in size, but in most instances they 

 had almost cimpletely dispersed before the bottom was reached. 

 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 a-certained. It will 

 thus be seen that there is ud attempt whatever on the part of the 

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

 the female is depositing the eggs at the bittim, the males con- 

 cern 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 little how 

 the currents are running, they are bound to carry some of the 

 milt towards the eggs, the milt, like the eggs, sinking- though 

 not alhering ta the bottom. 



This then is the natural process of depositing and fertilising 

 the ova of the herring in comparatively still water. When the 

 female had d .-posited a certain number of ejrgs at any given spot, 

 she moved forward in a somewhat jerky fa-hion without ri-ing 

 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 IJydrallmannia 

 sent from Eyemouth seems to indicate that the female moves 

 about amongst sea-firs and seaweeds in exactly the same way as 

 she does amon.;st stones. On each stem of the colory there is a 

 clu-ter of ova abiut the size of a small grape, and all theclusters 

 had reached on arrival the same stage of develojiment as if they 

 had been deposited about the same time and by the same fi~h. 



This method of depositing and fertilising the egjs accounts, I 

 think, for all the eggs, or at least for a very large percentage of 

 those found attached to sea-firs, seaweeds, and stones, containing 

 developing embryos. 



When a female was depositing her eggs, she was very easily 

 disturbed ; whenever anything was introduced into the tank she 

 at once darted off. When strong currents were made, she at first 

 seemed to apply herself nearer ta the bottom, to make sure, as it 

 were, that the spawn would get fixed before it cjuld be carried 

 away ; but when the currents were further intensified she at once 

 changed her position, and arrested the escape of the spanm. A 

 spawning fe nale was held immediately under the surface of the 

 water so as to cause the spawn toescape. When this was done the 

 spawn escaped in 1 jng ribbons coasistin^j of a single row of eggs. 

 So firmly do the eggs adhere to each other that in perfectly still 

 water the ribbon was sometimes over a foat in length before it 

 broke. Whan it had only about two feet of water to travel 

 through, it fell in wide loops at the bottom, but when it had to 

 fall over three feet the chain broke up into nunerous segments 

 which formed an irregular pattern on the bottam. From experi- 

 ments made, it seems the further the eggs have to fall and the 

 longer they are in contact with the water bef ire they reach the 

 bottom, they are more widely dispersed, and have all the le-s 

 adhesive power. When the eg<s are expressed in w-ater moving 

 rapidly in various directions, the chains saon break into shart 

 segments, and the individuil eggs and the small group; are often 

 carried a considerable distance before they reach the bottam. 



A number of flat stones and pieces of seiweed were obtained, 

 and a spawning female held over the.u at different distances in 

 still water, in water with gentle currents, and in water with strong 

 currents. In this way we obtained groups of eggs which 

 mimicked in a very striking manner all the arrangements of the 

 eggs on the stones and seaweeds dredged on the Ballantrae 

 Bank. When gently pressed, a beaded ribbon consisting of a 

 single row of eggs always escaped ; when there were no currents, 

 it formed a conical heap ; when in a gentle current, the ribbon 

 fell in irregular loops, the elements of which rearranged them- 

 selves so as to form a flattened cone ; but when strong 

 currents acted on it the ribbon wa; broken inta fragnents 



