464 



NATURE 



[February 14, 19 18 



LETTERS TO THE EDITOR. 

 [The Editor does not hold himself responsible foi 

 opinions expressed by his correspondents. Neither 

 can he undertake to return, or to correspond with 

 the writers of, rejected manuscripts intended for 

 this or any other part of Nature. No notice is 

 taken of anonymous communications.] 



Flights of Rooks and Starlings. 



I MAY be writing of what is so commonly linown to 

 naturalists as to be unworthy of record; the facts, 

 however, are new to me. On a fine, still day last Sep- 

 tember 1 observed a large flight of rooks attended, as 

 Gilbert White notes, by starlings. As they passed 

 across the sky both rooks and starlings mounted 

 higher and higher until they were lost to sight 

 in the distance. Whatever may have been the 

 occasion of the concourse, it was a subject of much 

 interest to rooks in general, for solitary birds hurried 

 by, cawing loudly, to join the main body. These be- 

 lated individuals mounted in fairly regular spirals. 



About a fortnight later I had the good fortune to 

 be able to follow with powerful glasses a similar flight, 

 biit of rooks unaccompanied by starlings. As before, 

 the mean movement in the still air ■ was a steady 

 oblique ascent, and the general impression that of a 

 crowd of birds the individual movements of which were 

 confused and irregular. This impression of confused 

 flight w^s, however, probably wrong, for the few indi- 

 vidual birds I was able to follow were undoubtedly 

 rising in fairly regular spirals. 



The surprising and, to me, novel character of the 

 flight did not appear until the birds had" risen to a 

 height beyond the limits of unaided vision. The move- 

 ments of individual birds then changed from the even 

 sweep of the spiral to what can only be called trick 

 flying. The wildest antics were indulged in, the com- 

 monest being a dive with closed wings, the bird some- 

 times rolling over and over. I could not fit the char- 

 acter of the movement to the hypothesis that the birds 

 were darting after insects on the wing. 



The two facts new to me were the height attained 

 and the fact that a bird of such sedate manners as 

 the rook should on occasion condescend to do "stunts." 



W. B. Hardy. 



The Athenseum Club, Pall Mall, 

 February 4. 



National Union of Scientific Workers. 



There is appearing in your advertising columns an 

 announcement relating to this Union ; will you allow 

 me space to explain its objects very briefly, but rather 

 more fully than is possible in an advertisement? 



There is a general agreement that it is imperative for 

 the best interests of science that those who pursue it 

 should possess 'greater political and industrial influence. 

 The founders of our Union believe that they can attain 

 that influence only by adopting the form of organisa- 

 tion which has proved effective in experience. That 

 organisation involves the formatiofi of a Union includ- 

 ing, so far as possible, every professional scientific 

 worker, and governed in a completely "democratic" 

 fashion. It is such a Union that we are trying to 

 form. 



In the pamphlet for which everyone is urged to write 

 further details of our aims and methods of attaining 

 them are suggested. But we feel that no self-appointed 

 body can possibly legislate permanently for a Union 

 designed to embrace the whole world of science. Our 

 Immediate endeavours, therefore, are to set up a pre- 

 liminary organisation which will lead to the summon- 

 ing of a thoroughly representative general meeting 

 having the authority necessarv to set the Union 

 NO, 2520, VOL. 100] 



on a permanent basis. The pamphlet is mainly 

 devoted to an account of this organisation. Until it 

 has done its work thg constitution and policy of the 

 Union will remain unsettled; we would urge accord- 

 ingly that any divergence, except on the fundamental 

 principle, from the views of the founders is an argu- 

 ment for, rather than against, taking part in the pre- 

 liminary work. 



One last point. We are often asked what is our 

 attitude towards other societies, existing or proposed. 

 Our answer is that, since none of them are both all- 

 inclusive and democratically governed, none, according 

 to our view, can do our work. But, of course, we 

 recognise that there are other ways of advancing the 

 cause of science which are being followed effectively 

 by other bodies. We recognise further that our rela- 

 tions to these other bodies will need careful considera- 

 tion and regulation ; but to discuss exactly what the 

 relations must be would be to exceed the space I can 

 ask you to put at my disposal. 



Norman R. Campbell 

 (General Secretary N.U.S.W.). 



North Lodge, Queen's Road, Teddington. 



THE GREEN LEAF: ITS SCIENTIFIC AND 

 ECONOMIC EXPLOIT A TION. 



THROUGHOUT the unnumbered ages which 

 have witnessed the rise and fall of successive 

 civilisations upon this planet, the one thing- that 

 has stood between mankind and extinction by 

 lack of food has been the activity of the chloro- 

 plast of the green leaf. Perhaps, before equal 

 time has again rolled over the world, the synthetic 

 production of food may have been achieved, and 

 man in all his intellectual glory may claim equality 

 with the lilies of the field. Until then the fixation 

 of organic carbon by "photosynthesis" In green 

 cells must, by us, be regarded as the basal 

 chemical happening oi our planet. Thousands 

 of years of empiric agriculture have enabled man 

 to exploit this aspect of vegetation with remark- 

 able success, but the problem of carbon assimila- 

 tion found its way into the laboratory only at the 

 end of the eighteenth century by the genius of 

 Priestley, and its broad aspects were first formu- ^ 

 lated by the wisdom of De Saussure in 1812. 



We may consider in this article what progress 

 has been made with this matter, as a problem of 

 pure and applied science, in the century that has 

 elapsed since then. The recent appearance of a 

 summary review of our knowledge of the subject 

 by I. J<^rgensen and W. Stiles^ gives a good 

 foundation for such consideration. 



Investigators have not been idle. The biblio- 

 graphy contains 250'entries, but these are not a tenth 

 of the papers published, for our authors' intention is 

 to ignore historical development and give only a 

 I critical account of those researches which mark 

 I the present advance line of knowledge on the many 

 I separate, but converging, roads by which this 

 j well-defended secret of Nature has been attacked. 

 The authors are as severely critical as the com- 

 missioners on a military campaign. They have 

 carefully thought over the aspects of the subject 



1 "Carbon Assimilation : A Review of Recent Work on the Pigments of 

 the Green Leaf and the Processes connected with Them." By Ingvar 

 J-^rgensen and Walter Stiles. JVeru P/iyio/o^/si Reprint, No. lo. Pp. i8o. 

 (London : Wesley and Son, 1917.) Price 4^. 



