RErORT ON THE SPAWNING OF THE COMMON SOLE. 5 



quarter or so of each ovary (reckoning from the head end backwards) 

 was dotted over with small bloodspots, answering to Holt's description 

 of the spent sole.* I presume, therefore, that this region of the ovary 

 was that from which, in the first three weeks or month of the spawning 

 season, the majority of the eggs had been derived. 



IV. The Act of Spawning. 



At the time of spawning the soles came to the very front of the 

 tank close to the glass, so that on a number of occasions I had a good 

 view of the process. 



The soles lay about on the bottom apparently indiscriminately, here 

 one by itself, there two, three, or more near together. One of them 

 would from time to time move leisurely to another place, and in passing 

 by or over one of its companions, would evidently take notice of it, as 

 by feeling it with the under side of its head, but this never led to any- 

 thing of the nature of pairing, such as some have imagined might occur 

 in the case of the sole ; for the fish would again move on and continue 

 the spawning process elsewhere, apparently regardless of the exact 

 position of its fellows, and preoccupied with its own share in the opera- 

 tion. Doubtless, however, such recognitions in passing are the outward 

 sign of the instinct whereby the fish assemble at the spawning time, so 

 that eggs and spermatozoa may rise together in the water, and fertiliza- 

 tion take place. 



In spawning the sole lay on the bottom of the tank, and raising its 

 head, brought it down again with force. This act involved a certain 

 agitation of the hinder regions of the body also, which was perhaps as 

 important as the more conspicuous movement of the fore part in as- 

 sisting the expulsion of the ova or spermatozoa, but the appearance was 

 as if the fish desired to create a splash of sand by the downward move- 

 ment of its head. The movement was quite different from that by 

 which soles commonly cover their upper side with sand, and had not 

 that effect. 



The eggs appear to be shed one at a time, each as the result of one of 

 the movements just described. It seemed to me that this movement 

 wafted the egg tailwards ; at least a fresh egg commonly appeared 

 above the tail of a fish after each of the head splashes described. 



I never actually saw the exit of either ova or spermatozoa from a 

 fish, but if the eggs are shed singly in the manner described, and tlie 

 spermatozoa in correspondingly small numbers, one could, perhaps, 

 hardly expect to ; and I think anyone who saw the eggs slowly rising 



* E. W\ L. Holt. "North Sea Investigations" (contd.), Journal of Mar. JIM. Jss. of 

 U.K., vol. ii. (N.s.), p. 371. 



