January 14, 19 15] 



NATURE 



533 



to our knowledge of materials. A chapter on the 

 general principles of design of the bow-girder is 

 included, and will be of ser\Mce to the practical 

 designer, to whom a considerable portion of the 

 volume will be sealed on account of necessarily 

 complicated mathematical treatment. The authors 

 may be congratulated on the success with which 

 they have solved a very difficult practical problem. 



Spectrum Analysis, applied to Biology and Medi- 

 cine. By the late Dr. C. A. Macmunn. Pp. 

 xiv+ 112. (London : Longmans, Green and Co., 

 1914.) Price 55. net. 

 The late Dr. Macmunn belonged to a class of 

 which British science does well to be proud : the 

 class of men who, notwithstanding the arduous- 

 ness of their professional labours, find or make 

 time to engage in research. Born in Ireland and 

 educated at Trinity College, Dublin, Macmunn 

 practised medicine for twenty years at \\'olver- 

 hampton, and during that period published his 

 researches in the application of spectrum analysis 

 to biology and medicine. The present work, as 

 we learn from the preface by Prof. Gamble, was 

 begun and continued between attacks of severe 

 illness and was left in an un revised state. 



Dr. Macmunn was an early worker in the field 

 and deserves the credit of the pioneer. Although 

 no remarkable discovery attended his efforts, he 

 contributed valuable observations on the nature 

 of the various colouring matters botn in animals 

 and in plants. He demonstrated that the pigments 

 of not a few animals contain chlorophyll : a 

 demonstration confirmed in certain cases by the 

 discovery of algae living symbiotically in the 

 tissues of these animals. 



Although the professional man of science who 

 specialises in this department of research may not 

 need to consult this work, we welcome it and 

 hope that it may be widely circulated and read, 

 for it is a worthy record of the labours of one who 

 loved research and ensued it with ardour and 

 success. 



The Geographic Society of Chicago, Bulletin No. 



4. The Weather and Climate of Chicago. By 



Prof. H. J. Cox and J. H. Armington. Pp. 



XXV + 375. (Chicago: University of Chicago 



Press, 1914.) Price 125. net. 

 Messrs. Cox and Armington have made a statis- 

 tical study of the climate of Chicago of extraordin- 

 ary detail. The result is valuable as a book of 

 reference, but cannot be described as easy read- 

 ing, chiefly owing to one hundred and forty-five 

 tables intercalated in the text. Records of tem- 

 perature extend back to 1830 and of rainfall to 

 1S43, but the series are not homogeneous, there 

 being several changes even in the shorter period 

 1871 to 191 1, which is adopted for normal values. 

 Normals, however, are not regarded as so im- 

 portant as the occurrences of abnormal conditions 

 and rapid variations which render the climate 

 healthful and invigorating — and with a tempera- 

 ture range from — 16° to + 103° F. there is abun- 

 dant room for rapid changes. The extremes would 

 be even greater but for the near neighbourhood of 



NO. 2359, VOL. 94] 



Lake Michigan, as is well shown by a study of 

 the lake breezes, and by temperature records at 

 different distances from the shore. The abnormal 

 periods are further considered, not merely locally, 

 but as part of the weather of the whole States, and 

 this aspect is illustrated by reproductions of the 

 daily synoptic charts, unfortunately sometimes so 

 small as to be almost undecipherable. Full use is 

 made of isopleth diagrams for exhibiting hourly 

 variations ; a feature with less to recommend it is 

 the replacement of departures from normal tem- 

 perature by accumulated departures, which are 

 said to be " more vivid " — though it is not self- 

 evident that an " accumulated " departure of 

 + 1262° conveys more to the mind than a mean 

 departure of -r3i°. 



LETTERS TO THE EDITOR. 

 [The Editor does tiot 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."] 



Experiments on Hay Infusions. 



Dr. Bastian's interesting experiments suggest 

 further considerations, particularly as to the osmotic 

 effects of solutions of different strengths and tem- 

 peratures. A solution of hay made at a higher tem- 

 perature will probabK' be a stronger solution con- 

 taining more soluble matter, and also more silicate 

 from the glass. A solution kept for a fortnight may 

 evaporate and become more concentrated. Does one 

 concentration produce Zoogloea, and a greater con- 

 centration produce spores? 



Am I right in thinking that the general effects- of 

 increasing concentration are crystallisation, precipi- 

 tation, an increasingly dense protoplasm, a thicken- 

 ing cell-wall, and cell subdivision? Is free-cell forma- 

 tion another process brought about by increasingly 

 concentrated solutions? Is dilution, and especially 

 dilution with warm water, the necessary osmotic 

 condition for bursting the cell-wall and liberating 

 naked or amoeboid forms? Can we explain the 

 phases of an organism in terms of its previous history 

 and present conditions? 



Where a change takes place in the population of a 

 pond this may, of course, be due to individual trans- 

 formations of tadpoles into frogs with rise of tem- 

 perature, or it may be due to differential rates of 

 increase or death, as when in a dry summer stickle- 

 backs die and frogs survive. It is not quite easy- to 

 disentangle the transformation and the survival pro- 

 cesses when the organisms are minute. j 



Hugh RichardsonI 



Stocksfield-on-Tyne, December 31, 1914. 



THE ASCEXDIXG SPIRAL.'^ 



TVyTAXY years ago the author of this interesting 

 ^^^ and stimulating book became impressed 

 with the widespread distribution of " spirals " in 

 nature. He has persistently followed the clue in 

 the hope of discovering the significance of this 

 form, which is ever-recurrent, especially in the 

 realm of organisms. Many others have been on 



1 " The Curves of Life. Being an Account of Spiral Formations and their 

 Application to Growth in Naiurr. to Science and to .\rt ; with Special 

 Rtference to the Manuscripts of Leonardo da Vinci." By T. A. Cook. Pp. 

 xxx+47g. (London : Constable and Co., Ltd., 1914 ) Price 12s. td. net. 



