February 3, 1916] 



NATURE 



619 



naturalists. It is unfortunate that the abundant 

 illustration should have been permitted to justify 

 the heavy, thickly loaded paper used throughout 

 the book. Apart from this distressing feature, the 

 printing is good and clear, and there are not many 

 errors, among which, however, " Neandertal," 

 "Axolotyl," and "trachea" for the plural (p. 71) 

 were noticed. The figures are sometimes good.- 

 and mostly adequate, a small proportion being 

 distinctly bad. In some of them the description 

 fails to account for the whole of the reference 

 letters. 



In speaking of the analogical groups of 

 the Australian Marsupials (on p. 130), the 

 wombat as a representative of the Rodents is an 

 obvious omission (probably the author intended 

 wombat when he wrote bandicoot) ; and in assert- 

 ing that there are no marsupial bats, the flying 

 phalangers should have been mentioned as 

 analogous to the flying squirrels. The statement 

 that the size of insects is " somewhat strictly 

 limited " (p. 71) might have been modified by a 

 reference to Carboniferous times, when these 

 forms had the air to themselves. 



We believe, in spite of the faults to which atten- 

 tion has been directed, that the book will be 

 useful because of the wide ground covered, the 

 good selection of examples, and the brevity and 

 clearness of the text. E. B. P. 



The Gases of the Atmosphere : The History of 

 their Discovery. By Sir William Ramsay. 

 Fourth Edition. Pp. xiii + 306. (London : 

 Macmillan and Co., Ltd., 1915.) Price 65. net. 

 Just complaint has been made recently in 

 N.'VTURE of the dearth of good modern popular or 

 semi-popular literature calculated to inform the 

 public of the methods and achievements of natural 

 science. Nothing could be better for this purpose 

 than Sir William Ramsay's book on "The Gases 

 of the Atmosphere," for here we have a first-hand 

 account of modern discoveries in a connected and 

 highly interesting narrative, and presented in a 

 sufficiently elementary style to make the subject 

 intelligible to a large leading public. 



Since the book appeared in 1896 a second and 

 third edition have been issued, keeping the story 

 abreast of discovery. In this, the fourth, edition 

 there is not much new matter beyond an account 

 of the remarkable work done by the author and 

 Dr. Whytlaw-Gray on niton. The passage of the 

 story from a record of the intrepid and masterly 

 discovery and isolation of the companions of argon 

 into the realm of radioactivity and modern alchemy 

 is perhaps natural and excusable to the author; 

 but it has the effect of a change of key, and causes 

 a fine record of fact to conclude on a note of 

 speculation. 



It is impossible in reading this history of the 

 gases of the atmosphere, in which very even 

 justice seems to be done to all discoverers, not to 

 be struck by the honourable part which has been 

 borne by British men of science. Boyle, Mayow, 

 Black, Priestley, Cavendish, Ramsay, and Ray- 

 leigh ; to these add Scheele and Lavoisier, and no 

 name remains to attach to any capital discovery 

 XO. 2414, VOL. 96] 



about the chemistry of the atmosphere. Without 

 in the least wishing to fall into the evil habit of 

 belittling German chemistry, one may be excused 

 for remarking upon its inconspicuousness in this 

 particular field of work. A. S. 



LETTERS TO THE EDITOR. 



[The Editor does not hold himself responsible for 

 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.] 



Colourless Crystals of Haemoglobin. 



May I have some of your valuable space in order 

 to put a question to physiologists and physicists whom 

 I could not reach so conveniently in any other way? 



For a long time I have been piuzzled by the existence 

 of colourless — white — crystals of haemoglobin. If one 

 carries out the familiar experiment of mixing a drop 

 of rat's blood and water on the microscopic stage, one 

 finds that while the majority of the crystals grow out 

 as reddish needles, a few crystals appear to be with- 

 out colour from the first. But more striking still : 

 I have in my possession a preparation of guinea-pig's 

 blood in which, amongst the beautifully formed, deep 

 red, regular tetrahedra (in which form that animal's 

 haemoglobin crystallises), there are a few crystals quite 

 as well formed as the rest which are perfectly white. 

 The preparation is two years old; originally all the 

 crystals were red ; only a few have become bleached 

 during the last year or so. It may be suggested that 

 the preparation has been unduly exposed to the light; 

 this is not so; except when occasionally examined it 

 has been in the dark. 



But what ti- colourless haemoglobin? Physiologists 

 do not know it, or at least they have not described it. 

 Colourless haemoglobin in the above sense is not men- 

 tioned in the exhaustive monograph of Reichert and 

 Brown. So far as I can learn, no leuco or colourless 

 state of haemoglobin is recognised analogous to the 

 leuco state (reduced state) of haemocyanin, a blue 

 respiratory pigment, or to the leucoplastid condition 

 of chromoplastids in plants. 



Can these crystals of guinea-pig's blood be regarded 

 any longer as haemoglobin seeing that all trace of 

 colour or pigment has vanished from them? Is there 

 such a thing as colourless haemoglobin ; are these 

 things not contradictory terms? There is no question 

 here of the removal of haematin or of iron from the 

 crystals. The crystals have not been in contact with 

 living tissues or with any active chemical substlinces 

 at all. Haemoglobin in old blood-clots, etc., in the 

 living tissues is converted by the removal of iron into 

 haematoidin, which, though not always cn,'stalline, is 

 always coloured. Reduced haemoglobin we know, but 

 it is still a coloured substance (purple), still a pigment ; 

 it has a spectrum. If these white, crystalline forms 

 are not haemoglobin, what are they? .4nd if they are 

 still haemoglobin, the essence of which is to be a pig- 

 ment with a spectrum, how can haemoglobin be 

 colourless? The bush that burned and was not con- 

 sumed is simple compared with the problem here. 



D. Eraser Harris. 



Dalhousje University, Halifax, N.S., 

 January 12. 



Asteroids Feeding upon Living Sea-Anemones. 



The following instances of asteroids feeding upon 

 living sea-anemones may be of general interest. 

 On October 27 three healthy examples of the sun- 



