NATURE 



[March 3, 19 10 



inevitable result is a dismal failure. It is not quite 

 clear for what class of reader the work is really 

 intended, for in the preface we read that it "is in- 

 tended to be a source of information and ready refer- 

 ence for the textile chemist," while on the title-page 

 it would appear from the continuation of the main 

 title, " bein^ the svllabus of a lecture course adapted 

 for use in textile laboratories," that it mi^ht be in- 

 tended for some other purpose, possibly for teaching. 

 In either case it has missed its mark. 



These "knowledge in a nutshell" publications on 

 technical chemistry, of which there appears to have 

 been an increasing supply of late years, may be just 

 the sort of thing that please people who like that 

 sort of thing, but although there are a few exceptions, it 

 is doubtful whether they do much good, while, on the 

 other hand, they may do distinct harm through 

 creating, under pVetent'ious titles, a totally misleading 

 impression of the subject as it presents itself in actual 

 practice. 



Naturwissenschaftliches Vtiterrichtswerk fiir hohere 

 Mddchenschulen. By Prof. Dr. K. Smalian. Auf 

 Grund der Bestimmungen vom 19 December, 1908, 

 iiber die Neuordnung der hoheren Miidchenschul- 

 wesens in Preuszen bearbeitet von K. Bernau. II 

 Teil : Lehrstofi" der VI Klasse. Pp. 80. Preis 1.80 

 marks. Ill Teil : Lehrstoff der V Klasse. Pp.127. 

 Preis 2.25 marks. (Leipzig: G. Freytag; Vienna: 

 E. Tempsky, 1909-10.) 

 In the earlv part of last year a notice appeared in 

 Nature of Dr. Smalian 's '" Leitfaden der Tierkunde 

 fur hohere Lehranstalten," a work comprising a 

 zoological text-book in separate fasciculi intended for 

 the use of the various classes in German high schools. 

 The fasciculi now before us form part of another 

 work designed on somewhat similar lines for the use 

 of girls' schools, but including botany as well as 

 zoology. The general commendation bestowed on the 

 " Leitfaden" may be extended to the present text-book, 

 with the addition that we have little fault to find with 

 the coloured plates of animals, while those of plants 

 are excellent examples of German colour-printing, and 

 worthy of all praise. Each of the two fasciculi now 

 before us is divided into a botanical and a zoological 

 portion ; and it may be presumed that the same holds 

 good for the other portion of the series. The zoo- 

 logical section of the second fasciculus is devoted to 

 vertebrates, and that of the third to arthropods. A 

 number of well-known species of mammals are, how- 

 ever, described in the first fasciculus. 



The general plan of the work is similar to that of 

 the "Leitfaden," the various orders being treated in 

 systematic order, and a certain number of typical 

 species being selected for comparatively full notice, 

 while other groups are treated more briefly. In the 

 case of the species selected as types, leading features 

 in the external form and structure and noticeable 

 traits in the matter of habits are touched upon ; and 

 throughout the work technicalities are, so far as 

 possible, avoided. The only scientific names intro- 

 duced are those of species, ordinal and family groups 

 being referred to by vernacular designations. In the 

 main the species represented in the illustrations seem 

 to be correctly named ; but in one of the coloured 

 plates the monkey designated Cercopithecus sabaeus 

 is clearly C. aethiops or one of the allied forms, as it 

 has the distinct white brow-band of the latter, which 

 is absent in the former. So far as we can see, the 

 book appears admirably suited for its purpose, 

 although it by no means follows that it would be 

 equally well adapted to the needs of English 

 schools. 



XO. 2105, VOL. 83] 



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.] 



The Meaning of " lonisation " 



In asking for precision of language (p. 487), Prof. Arm- 

 strong shows how much he has fallen behind his time. 

 If he had kept abreast of the recent developments of the 

 principles of science, he would know that to be precise 

 means running the risk of being wrong, which is to be 

 avoided at all costs. Prof. Armstrong evidently belongs 

 to an antiquated school which believed that scientific dis- 

 coveries are made by forming definite ideas of things, even 

 though these cannot be seen and handled. That is a 

 standpoint which is abandoned, and we have entered on a 

 new era. Science now aims purelX"''at obtaining an equa- 

 tion which, without committing itself to any definite views, 

 gives the required relationship between the brain 

 impressions taking place in that particular dimension of 

 a many-dimensional complex, which we identify with time. 

 I am sorry if in this statement I have committed myself 

 to the existence of a brain — it was lapse due to a weak 

 concession to the prejudices of my youth, and would have 

 been impossible in a thorough-going adherer to the new 

 faith. 



But to come to the point. If Prof. Armstrong will 

 bring the theory of entropy to bear on the principle of 

 least resistance to a cheap appearance of sagacity, he will 

 discover, not what Arrhenius meant by ionisation — that is 

 unimportant — but what he ought to have meant and would 

 have meant if he were a chemical physicist such as we 

 make them now. A. S. 



The Fertilising Influence of Sunlight. 



The letter on the above subject by Mr. and Mrs. Howard 

 in Nature for February 17 raises a question of much 

 scientific interest and of considerable importance in tropical 

 agriculture. In some of the text-books it is stated that 

 the hot sunshine of tropical or subtropical climates must 

 injure the productiveness of the soil, since it kills bacteria. 

 On the other hand, experiments on the partial sterilisation 

 of soil by other means — such as heat or volatile antiseptics 

 — shows that the killing of bacteria (as distinct from spores) 

 leads to an increased, and not a diminished, productive- 

 ness. The apparent discrepancy is now cleared away, and 

 we have Mr. and Mrs. Howard's authoritative statement 

 that strong sunlight has beyond question a beneficial effect 

 on productiveness. 



There is a close resemblance between the effects they 

 describe and those that have been obtained with partially 

 sterilised soils by myself in conjunction with Dr. Darbi- 

 shire and with Dr. Hutchinson ; in all cases the effect 

 is that of a dressing of nitrogenous manure. Dr. Hutchin- 

 son and I have traced this to an increased rate of de- 

 composition of organic matter after partial sterilisation, 

 and have shown that the increased activity is due to the 

 destruction of some agent, probably large organisms, which 

 had previously interfered with bacterial development. The 

 question is, Could sunlight partially sterilise a soil and 

 kill the large destructive and competing organisms that 

 we suppose limit productiveness? 



There are at least three factors involved : sunshine dries 

 the soil, heats it to a certain temperature, and may havr- 

 a direct chemical action fatal to the cell. We are at pre- 

 sent studying the effect of dryness and of temperaturps 

 lower than 100° (at which we have previously worked), 

 but the direct effect of sunshine is not easily investigated 

 here. Some preliminary experiments I made at Wy 

 during the summer of 1906 indicated that soil exposed to 

 bright sunshine for a period of ten davs subsequently 

 absorbed oxygen more rapidly, i.e. showed a higher rat-^" 

 of bacterial activity, than another lot kept shielded from 

 the light. The effect was comparable with that produced 

 by volatile antiseptics, and, so far as the experiment goes, 

 it shows that sunlight could, equally with these, remove 

 the factor limiting productiveness in ordinary soils. T 

 have several times attempted to extend the experiment, but 



