December 9, 1922] 



NA TURE 



765 



endeavoured to present the ascertained facts in a 

 collected form in order to lead up to a working ideal, 

 believing that premature analysis had always proved 

 unfortunate. For two generations now the general 

 ideal of our atmosphere has been that of a succession 

 of travelling cyclonic vortices and anticyclonic areas. 

 Hildebrandsson and Teisserenc de Bort provided a 

 normal permanent circumpolar vortex in which travel- 

 ling cyclones might be formed. But the ideal presented 

 is still inexcusably vague and undeveloped : there is 

 much to be done before we can say even what we ought 

 to look for in a map if we wish to identify a vortex 

 travelling under the normal conditions of the atmosphere 

 and we are not yet ready to do justice to that ideal. 



Prof. Bjerknes on the other hand has set out to 

 prove that our maps can be simulated or stimulated 

 by wave-motion on either side of a surface of dis- 

 continuity which separates equatorial air from polar 

 air. Here we may note a tendency to follow 

 another Greek maxim, this time of Aristotle, " for 

 those things which escape the direct appreciation of 

 our senses, we consider we have demonstrated them 

 in a manner satisfactory to our reason when we have 

 succeeded in making it clear that they are possible." 



In " Weather Prediction by Numerical Process " 

 Mr. Richardson follows a line of thought which differs 

 widely from either of these. His main simplifications 

 are to divide the atmosphere into his 16,000 slabs 

 and to ignore perturbations which are on a smaller 

 scale than a hundred miles. The rest is rigorous. 

 The principle which lies at the bottom of his treatment 

 of the subject is that the known laws of dynamics 

 and physics as applied to the changes which take 

 place are inexorable and are sufficient. The future 

 can therefore be derived from the present by their 

 application. They can be applied by the step by step 

 method of finite differences with sufficient accuracy to 

 obtain the general consequences of the present condi- 

 tions. The illustration of the process is a most valuable 

 contribution to meteorology and indicates a wholesome 

 course of practical physics and dynamics of the atmo- 

 sphere which may prove the basis of future teaching. 

 Thus it will not only provide an acid test of meteoro- 

 logical theory but also be a valuable guide to the 

 organisation of new meteorological observations. 



Finally, perhaps the most important aspect of this 

 contribution to meteorological literature is that a 

 rigorous differential equation is not necessarily useless 

 because it cannot be integrated algebraically. It opens 

 the way to useful exercises less stupendous than 

 calculating the weather, and indeed, whenever meteor- 

 ology comes to be taught and learned, the book will 

 be a rich quarry for the teacher and examiner. 



Napier Shaw. 

 NO. 2771, VOL. I IOj 



Parker and Haswell's "Zoology." 



A Text-book of Zoology. By the late Prof. T. J. Parker 

 and Prof. W. A. Haswell. In Two Volumes. Third 

 Edition. Vol. I., pp. xl + 816. Vol. II., pp. xx 

 + 714. (London: Macmillan and Co., Ltd., 1921.) 

 50^. net. 



WHEN a demand arises for a new edition of a 

 general text-book on some branch of science, 

 the problem before the editor is to decide whether the 

 new wine of recent discovery will go with safety into 

 the old bottle. The solution depends largely upon the 

 adaptability of the original scheme. When the treat- 

 ment has been dominated by one aspect of the subject- 

 matter, or when the science has entered on a new 

 transitional phase of discovery involving new points 

 of view, the new wine requires a new bottle. 



Parker and Haswell's " Text-book of Zoology " 

 illustrates this difficulty. Its outlook on the great 

 and varied theme of animal life is fixed on the static 

 anatomical aspect, on the intensive analysis of indi- 

 vidual structure, and on the grouping of animals 

 in classes according to structure. So fascinating and 

 so adaptable to educational discipline is this pursuit 

 that the anatomical aspect is only too apt to dominate 

 other and equally important methods and aspects of 

 animal studv. It is against this over-emphasis of 

 descriptive anatomical detail that teachers of zoology 

 have been protesting for many years, with the result 

 that in practice there is a more balanced consideration 

 of the dynamical as opposed to the statical aspect of 

 zbology. 



In this respect the new " Parker and Haswell " is 

 disappointing. The rigidity of its structure has pre- 

 vented its editor from adapting the text of these two 

 volumes to modern requirements, or from embodying 

 more than a very small amount of the new matter and 

 none of the new points of view that zoologists have 

 discovered in the last twenty years. The chief revision 

 is limited to three groups of Invertebrates — the Nema- 

 todes, Polyzoa. and Annelids — while the whole of the 

 second volume — the Vertebrates and the philosophy 

 of zoology — has, so far as can be readily ascertained, 

 undergone little change. 



Ungrateful as is the task of adverse criticism, it must 

 be acknowledged that this revision has not gone far 

 enough. In contrast to the vigorous handling of the 

 Platyelmia and Annelids, the loose treatment of the 

 Nematoda is very pronounced. The account of 

 the life-history of the common Ascaris is both wrong 

 and misleading, and the description and figure of the 

 hook-worm are most inadequate. In fact, in regard to 

 parasitology generally, one has but to compare the 

 little book recently published by M. Caullery and 



2A I 



