August 13, 1908J 



NA TURE 



il'-) 



Dr. Konen's chapter on fluorescence is again ad- 

 mirable, and is also prefaced with an historical section, 

 from which may be gathered the interesting informa- 

 tion that the first mention of fluorescence is an account 

 which Robert Boyle found in a Spanish manuscript 

 dated 1570 of an aqueous extract of some wood. 



The second section of this chapter deals with the 

 so-called bright-line fluorescence spectra, including, of 

 course, the work on iodine and Prof. R. W. Wood's 

 jiew work on sodium vapour. Tliis opens the ques- 

 tion as to w'hat is meant by fluorescence, for it would 

 seem that the phenomena of bright-line spectra ob- 

 tained with iodine and sodium vapours are of a difTer- 

 «nt order from the true fluorescence of organic 

 compounds. Wood's more recent work would cer- 

 tainly go far to show that his results are those of 

 optical resonance pure and simple. On the other 

 hand, the real fluorescent phenomena of organic 

 chemistry are of a very different nature. They are 

 undoubtedly due to a certain complexity of structure; 

 they undoubtedly require a linking together within 

 the molecule of a definite number of centres of un- 

 saturation (used in the chemical sense). Conversely, 

 a simplification of the molecular structure tends to 

 decrease the power to fluoresce. The two pheno- 

 mena must therefore be of different type, and for this 

 reason it would be preferable to treat the bright-line 

 phenomena under a separate heading of resonance 

 spectra, leaving the term fluorescence to the more 

 complicated molecular phenomena of organic 

 chemistry. 



Following on the section upon bright-line fluor- 

 escence there are sections dealing with ordinary band 

 fluorescence spectra, the method of investigation, the 

 absorption and emission of fluorescing substances, 

 the influence of temperature, of the solvent, and of 

 the wave-length of the exciting light, and, finally, two 

 .sections dealing with the relation between fluorescence 

 ;md chemical constitution, and also with general 

 theories. A list of substances is added which are 

 known to exhibit fluorescence, a list which, though 

 far from complete, is a very useful addendum. This 

 list brings to conclusion a volume which is a worthy 

 follower of the three volumes which have preceded it. 



?OVVLkR ORNITHOLOGY. 



(i) A Bird Collector's Medley. By E. C. Arnold. Pp. 

 iv-hi44; with 12 coloured and 8 collotype plates and 

 illustrations in the text. (London : West, Newman 

 and Co., 1907.) Price io.<f. 



(2) Birds of Britain. By J. Lewis Bonhote. Pp. 

 X+405; with 100 illustrations in colour. (London: 

 .\dam and Charles Black. 1907.) Price 20s. net. 



<3) .4 Book of Birds. By W. P. Pycraft. Pp. viii + 

 155; with 30 full-page coloured plates and illustra- 

 tions in the text. (London : Sidney .\ppleton, 190S.) 

 Price 6s. net. 



(i) TV /T R. .ARNOLD has been known for several years 

 •'-'-'■ past in the bird world as an enthusiastic 



shore-shooter who has been lucky enough in recent 



years to secure examples of several migratorv birds 



which have very rarely been known to straggle to these 



NO. 2024, VOL. 78] 



shores, and, indeed, to add two species to the British 

 list. He very ably justifies the killing of these rare 

 migrants on the grounds that they are abnormal 

 wanderers which would never settle in England, and 

 adds that it seems far better that they should be care- 

 fully preserved for the benefit of those who would 

 otherwise never see them rather than be observed 

 through glasses by one individual for the space of 

 perhaps half an hour at the outside. His introductory 

 chapter is mainly taken up by a forcible defence of 

 the amateur collector, who, he very truly says, is 

 abused by books, periodicals, newspapers, and those 

 verv ladies w-ho adorn their bonnets with stuffed terns 

 and bullfinches. What is more contemptible is the 

 attitude of " some eminent naturalist, who has possibly 

 amassed a fine private collection in his \oulh, and has 

 now taken up the fashionable cry." We were re- 

 minded of the truth of this " reprisal " upon reading 

 quite recently a review- of this very book. .\ chapter 

 on bird-protection deserves careful perusal. It is an 

 able summary of the whole matter, so far as it con- 

 cerns this country, and contains more common-sense 

 and less rubbish (we had almost written hypocrisy) 

 than any other disquisition on the subject we have 

 met with for a long time. For the rest, the book is 

 chiefly an account of the author's personal experience 

 as a field ornithologist and collector in many and 

 varied parts of the British Islands, and contains many 

 very interesting notes and observations. 



One of the best chapters reja-tes the experience of a 

 dunlin, born on the fells, going down to the seashore 

 for the winter and back to the moorlands in spring, 

 and is very well told indeed (in the dunlin's own 

 words). There is also a good chapter on bird-stuffing, 

 and a medley was, a good name for the book. The 

 twenty full-page plates, the work of the author, 

 portray some pleasing scenes in bird-life. Some also 

 are intended to recall specimens of rare birds in the 

 author's bird collection in the Eastbourne Institute. 

 No one w-ould wish to criticise their merits too closely ; 

 it is enough that for the most part they appeal to the 

 emotions of the field ornithologist. 



We must protest, however, agamst the plate of the 

 two ruffs in full breeding dress fighting at their breed- 

 ing grounds. Anyone who has watched ruffs on the 

 " hill " must have been struck especially with one cir- 

 cumstance, viz. the great diversity in colour of the 

 birds, and that from perhaps a dozen or so collected 

 on the hill at one time it would be impossible to pick 

 out two the colours and arrangement of colours of 

 which were alike. We cannot, therefore, but regard 

 the present picture displaying only two ruffs, and those 

 practically as alike as two peas, as unnatural. For 

 although such a case is not, of course, absolutely 

 impossible, it is extremely unlikely. The various 

 illustrations in the text are from photographs, and 

 some of them, e.g. "Doing the Bushes," will recall 

 days spent in that now famous spot to the minds of 

 many birdmen. The addition of an index would have 

 been an improvement to this nicely-got-up volume. 



(2) Messrs. Adam and Charles Black have added to 

 their series of beautiful books, with full-page illustra- 

 tions in colour, a volume on " Birds of Britain." The 



