1899] ON CILIARY MOVEMENT 351 



movements of the cilia, or to speak of the theoretical bearing of the 

 results, but we can honestly certify that as a douche the apparatus is 

 of the highest practical value. We have no wish to throw cold water 

 upon Professor Herrera, but we would like to mention that he certainly 

 performed the operation very successfully upon us. Indeed, when 

 once again the editorial person was restored to comfort and dryness, a 

 sudden suspicion flashed upon us that perhaps the instrument had been 

 tampered with in transit, and that some enthusiast, too hardly treated 

 in these pages, was now avenged, having successfully returned quid 

 pro quo. 



The Justification of Sea-Fish Hatching. 



The recent rapid development both in this country and America of the 

 practice of artificial hatching of sea-fish eggs, has, naturally enough, 

 raised up critics who question the economic value of the process. In 

 the " Eeport for 1898 on the Lancashire Sea-Fisheries Laboratory," 

 Prof. Herdman devotes several pages to a consideration of one of these 

 criticisms. His paper is of much interest, especially when taken 

 in conjunction with the account given elsewhere in the report of the 

 work done at the hatchery at Piel. The critic, Mr. Fryer, in the 

 " Twelfth Annual Pieport of the Sea-Fisheries Inspectors for England 

 and Wales (1898)," discusses the methods and results of American 

 hatcheries as disclosed by their annual reports, the discussion tending 

 to disprove the usefulness of sea-fish hatching in general. 



As to methods, special emphasis is laid on one point. It is well 

 known that two plans have been adopted to obtain eggs for hatching 

 purposes. The one, that hitherto practised at Piel, consists in obtain- 

 ing spawning fish from trawlers, or floating eggs from the surface ; 

 the other, as practised in most of the older stations, consists in keeping- 

 mature fish in captivity in spawning ponds until they breed. Mr. 

 Fryer argues strongly in favour of the former course, urging especially 

 that there is every reason to believe that the captive fish breed 

 more rarely and produce fewer ova than they would under natural 

 conditions. In other words, he argues that however successful the 

 hatching operations, the resulting fry are far less numerous than they 

 would be under natural conditions. On the other hand, Prof. Herd- 

 man points out that the work at Piel has proved, if indeed it needed 

 to be proved, that the difficulties in the way of collecting eggs from 

 trawled fish are so great as to reduce the chance of successful 

 hatching almost to a minimum — experience shows that a spawning- 

 pond is an indispensable adjunct to a successful hatchery. Further, 

 as Professor Herdman shows, Mr. Fryer's argument fails to take 

 account of the heavy risks of elimination to which breeding fish, ova, 

 and fry are alike subjected in natural conditions. So convinced is 



