32: 



NA TURE 



[January 13, 19 10 



occur? Is there a relation between the times of maxima 

 of different groups of plants or animals? We can hardly 

 look to qualitative plankton work for the answers, and it 

 has been the quantitative methods that have mapped out 

 the spring maxima of diatoms and dino-fiagellates, and, in 

 opposition to qualitative results, have shown how in 

 temperate and arctic regions the plankton is greater in 

 volume than in the tropics. 



Again, in order to show whether the changes in the 

 plankton are due to inherent qualities in the organisms, 

 to external influential hydrographical conditions, or to both, 

 a combination of hydrographic and planktonic work is re- 

 quired. It is, I think, obvious that there are many 

 problems awaiting solution, and our choice is limited to 

 the alternative of either leaving them alone or adopting 

 quantitative methods. 



It has been said that the latter are inaccurate. Of 

 course they are, to a certain extent, but unfortunately we 

 have no better at our disposal, and have considered it 

 better to use the most accurate methods possible, and to 

 remember the error when drawing our conclusions, than 

 to leave the whole question alone. It is significant that 

 all the objections, backed by scientific evidence, which 

 have been brought against the quantitative methods have 



I itj. 4. — The Closing Petersen-Hena 



; down open. 



come from investigators using these methods. It is obvious, 

 therefore, that their eyes are open to the defects of the 

 methods and the limits of the apparatus used. In this 

 respect may be mentioned the work of Lohmann and 

 Kofoid on the catching power of the nets (Fig. 4), and of 

 Herdman in regard to the variations in uniformity in the 

 (Hstribution of the plankton, which question was the first 

 to be considered in the Port Erin work. I cannot do better 

 than quote certain lines from the article in the report re- 

 ferred to : — " With the object of formulating such views 

 as to the nature of the Plankton at any particular time, 

 and as to the changes, both diurnal and seasonal, and the 

 determining factors of such changes, we must endeavour 

 to make quantitative catches as accurately and as fre- 

 quently as possible, so that our samples may be as nearly 

 representative and as nearly comparable one with another 

 as the difficult conditions will admit. These catches should 

 he made with standard nets, should be preserved and 

 measured according to a uniform .system, and may then 

 be compared in bulk ; but, in addition, the more important 

 organisms should be counted approximately, and the results 

 in round numbers may be used in comparing catches or 

 tracing changes ; but such figures should not be made the 

 NO. 2098, VOL. 82] 



basis of calculations as to the total numbers of such 

 organisms in the oceans." The last sentence cannot be 

 too strongly emphasised ; the quantitative method is not 

 used with the object of determining the number of diatoms 

 in the Irish Sea, and comparisons of figures obtained in 

 a uniform way should be the feature of the system. 



It would be of great value if some system could be 

 arranged so that plankton catches made in a uniform 

 manner could be taken in different parts of the Irish Sea 

 and St. George's Channel simultaneously. This would 

 greatly help in mapping out the distribution of the plankton 

 and tracing the course of the maxima. For example, in 

 July last, after weeks' of catches containing a normal and 

 small number of various copepoda, echinoderm larva;, &c., 

 the nets one day were found to contain large masses 

 of Calanus helgolandiciis. The catches were almost pure, 

 and, in fact, practically useless for the echinoderm larvae 

 that were wanted. This condition of affairs lasted from 

 two to three days, and then the Calanus swarm dis- 

 appeared as mysteriously as it came. Systematic and 

 simultaneous catches in the Irish Sea would have shown 

 over what area this Calanus swarm extended, and perhaps 

 whence it came. W". J. Dakin. 



PRIZES PROPOSED BY THE PARIS 

 ACADEMY OF SCIENCES FOR igii. 

 fZEOMETKY . — The Francceur prize (1000 francs), for 

 discoveries or works useful to the progress of pure 

 or applied mathematics ; the Bordin prize {3000 francs), 

 for improving at an important point the theory of triple 

 systems of orthogonal surfaces ; the Poncelet prize (2000 

 francs), for work in applied mathematics. 



Mechanics. — A Montyon prize (700 francs), for the 

 invention or improvement of instruments useful to the 

 progress of agriculture, the mechanical arts or sciences ; 

 the V'aillant prize (4000 francs) ; the subject for 1909, post- 

 poned to igii, is to improve the application of the prin- 

 ciples of the dynamics of fluids to the theory of the helix, 

 and the question proposed for igii is to perfect at some 

 point the study of the motion of an ellipsoid in an indefinite 

 liquid, having regard to the viscosity of the liquid. 



Navigation. — The extraordinary prize of 6000 francs, for 

 work tending to increase the efficiency of the French 

 naval forces; the Plumey prize (4000 francs), for improve- 

 ments in steam engines or for any other invention which 

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Astronomy. — The Lalande prize (540 francs), for the 

 most interesting observation, memoir, or work useful to 

 the progress of astronomy ; the Valz prize (460 francs), for 

 the most interesting astronomical observation made during 

 the current year ; the G. de Pont(5coulanl prize (700 francs) ; 

 the Damoiseau prize (2000 francs), subject postponed from 

 iqo9, the theory of the planet Eros based on known 

 observations, and for 1911, to perfect the "Tables de 

 Jupiter " of Le Verrier. 



Geography. — The Tchihatchef prize (3000 francs), for a 

 recompense or encouragement for exploration of the un- 

 explored or partially explored portions of Asia ; the Gay 

 prize (1500 francs), for the study of a French African 

 colony from the geological point of view (Algeria and 

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Physics. — The Hubert prize (1000 francs), for a dis- 

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 gress of physics ; the Gaston Plants prize (3000 francs), 

 for an important invention, discovery, or work in the field 

 of electricity. 



Chemistry. — The Jecker prize (10,000 francs), for work 

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 original chemical researches ; Montyon prizes (unhealthy 

 trades) (2500 francs and a mention of 1500 francs), for a 

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Mineralogy and Geology. — The Delesse prize (1400 

 francs) ; the Joseph Labb4 prize (looo francs), for geo- 

 logical works or researches le.ading to effective develop- 

 ment of the mining wealth of France, its colonies or pro- 

 tectorates ; Fontannes prize (2000 francs), to the author 

 of the best palaeontologieal publication. 



