September i8, 1919] 



NATURE 



49 



the plant side, is also subject to the influence of man's 

 fishing operations. These do not necessarily diminish 

 the total yield of fish : on the contrary, they are 

 probably powerless to affect the general balance, so far 

 as total productivity is concerned. But the elimination 

 of the larger fishes favours the survival of increasing 

 numbers of the small, since the stock of food remains 

 practically unchanged, while the enemies and competi- 

 tors of the small are progressively reduced. It follows 

 that the total numbers of the young of a given species 

 may be appreciably increased as a result of fishing 

 operations, through the progressive diminution of their 

 infantile mortality. 



Thus while the total quantity (weight) of the fish- 

 side of the balance of life probably remains constant, 

 its character may deteriorate sensibly. This deteriora- 

 tion is manifested not merely in the substitution of 

 large numbers of small fish for smaller numbers of 

 large fish of the same species, but also in the increasing 

 survival of relatively small and worthless species which 

 partly fill the gaps made by the progressive elimina- 

 tion of their larger competitors, e.g. dabs and long- 

 rough dabs in lieu of plaice and lemon soles. Signs of 

 this aspect of deterioration have been noticed in many 

 areas, e.g. the Scottish bays, the Devon bays. Dogger 

 Bank, etc. 



In the case of plaice, the young of which are re- 

 stricted to the coastal margins, while the adults range 

 freely within 30 fathoms or so, the general tendency of 

 intensive fishing is (a) to deplete the total densitv of 

 plaice on the offshore grounds., and (b) to increase the 

 number of small plaice along the shores. Thus large 

 areas offshore have been opened up for the multipli- 

 cation and growth of relatively worthless dabs, while 

 the increasing accumulations of the young inshore have 

 set up conditions of over-crowding, impoverished 

 growth, and delayed emigration to the offshore waters. 



The growth of a quantitative science of fish-life is 

 thus tending to the production of a co-ordinated body 

 of knowledge capable of deductive application to special 

 practical and administrative problems. The continued 

 growth of this knowledge is of the first importance 

 for the development of the sea-fisheries. Without it 

 administrators are at the mercy of every passing cry 

 and excited agitation ; with it, they will be enabled not 

 merely to estimate more accurately the value of parti- 

 cular suggestions, but themselves to inaugurate a new 

 era in the rational exploitation of the hitherto untamed 

 forces of the sea. It should be needless to add that the 

 value of particular investigations will have to be judged 

 in future, not from the point of view of the mere 

 resourcefulness of the sea, but from consideration of' 

 the extent to which they furnish means for intelligently 

 controlling it. Walter G.4Rstang. 



August 27. 



" Impoverishment " dies hard, and there is much 

 glamour around it. My able friend. Prof. Garstang, 

 commenced his campaign by showing tiiat the great 

 increase in the number of boats was accompanied by 

 a diminished catch in each, and that, therefore, there 

 were fewer fishes to catch than formerly, a view which 

 did not survive publication. His modified " Balance of 

 Life " will not rescue the Council from its responsibility 

 on the question of " impoverishment." 



The idea of gaining control of the " output " of the 

 sea, as in a mine or quarry, is a novel way of dealing 

 with the ponderous remit from the Government. 



Prof. Garstang. like the Council, stakes his position 



on the plaice, an old tale, and one which is not proven. 



Large plaice do not frequent, as" a rule, the areas of 



the smaller, and therefore the size is often a question 



NO. 2603, VOL. 104] 



of locality. For generations the same North Sea bay, 

 as, for instance, St. Andrews, will produce the same 

 sizes of plaice. Besides, adult plaice are not caught 

 napping when they see a trawl coming : hence the well- 

 known increase of the catch at night. 



The " measurably smaller fishes year by year " 

 probably refers to the boxes at Grimsby and otiier ports, 

 an uncertain basis for generalisations. Again, are the 

 herrings, gadoids, gurnards, mackerel, breams, wolf- 

 fishes, and frog-fishes, the turbot, soles, and dabs, get- 

 ting smaller year by year ? It is a mistake to aver that 

 dabs and long-rough dabs have anywhere usurped the 

 areas of the " vanished " plaice. 



•No possible comparison can be made between human 

 agencies in the hands of the farmer {in re cattle and 

 turnips) and the ways of Nature in the sea. Such would 

 not even fit the seals and the whales. The native farm- 

 weeds, such as "quicken" and "knot-grass," are 

 sufficient to illustrate Nature's powers. 



The facts given in the " Resources of the Sea " (a 

 second edition of which is ready for the press), stand 

 in little need of a " superstructure or co-ordinated body 

 of knowledge capable of deductive application to special 

 administrative problems." 



Truly, every encouragement is needed for scientific 

 fisheries researches in marine laboratories and else- 

 where. W. C. McIntosh. 



DR. A. G. VERNON HARCOURT, F.R.S. 

 P>Y the death of A. G. Vernon Harcourt, on 

 *~^ August 23, in his eighty-fifth year, there has 

 passed away a chemical teacher endeared to many 

 generations of Oxford students, a singularly 

 skilful experimenter, and a pioneer in the new 

 domain of physical chemistry. He was one of the 

 first who planned experiments to enable him to 

 follow the course of a chemical change, to 

 measure the velocity of a reaction, and to study 

 the conditions that determine it ; he rebelled 

 against the idea that chemists had to concern 

 themselves only with the preparation of new sub- 

 stances and the elucidation of their properties — 

 for him the interesting thing was how the change 

 happened, not what was the result. 



Starting with Brodie, first as his pupil and then 

 as his assistant, Harcourt began his researches 

 with the exact determination of the oxygen 

 absorbed by the metals potassium and sodium — 

 allowing air to enter slowly into a flask containing 

 the pure liquid metal heated in an atmosphere of 

 nitrogeii. In this first paper one can see that it 

 is the initiation and progress of the oxidation 

 that interest him. "Soon after the dry air has 

 begun to mix with the nitrogen, the grey film 

 which covers the molten metal changes to a deep 

 blue ; the surface gradually becomes roughened 

 by little wrinkles and projections, and a moment 

 arrives when a single spluttering spark appears 

 at one point and a dust of white oxide rises. 

 . . . At the point where the spark appears the 

 blue crust becomes white, and this change passes 

 in a moment over its whole extent." 



In 1859 Flarcourt was elected Lee's reader in 

 chernistry and a senior student of Christ Church, 

 but it was not until some years after his appoint- 

 ment that he began his work in the Lee's labora- 

 tory. Meanwhile he had started those researches 



