DISCOVERY 



191 



already noted, that the carbon dioxide evolved in 

 respiration is rapidly dissolved in the water ; in 

 consequence the air-bubbles may always be taken as 

 composed of oxygen and nitrogen alone. Now we 

 saw that a tension difference of 5 per cent, is required 

 for the resting needs of the animal, and the composi- 

 tion of the air in the store would then be 15 per cent. 

 oxygen and 85 per cent, nitrogen. These tensions 

 will be maintained by the uniform consumption of 

 oxygen and elimination of carbon dioxide. But the 

 nitrogen tension in the water is only 80 per cent., so 

 that nitrogen will diffuse out from the air-store into 

 the water and the bubble will disappear. In the mean- 

 time the oxygen diffuses in three times as quickly as the 

 nitrogen diffuses out, so that, by this means, the 

 insect procures thirteen times as much oxygen as it 

 originally carried. 



LIST OF PAPERS 



August Krogh, " Ein Mikrorespirationsapparat und einige 

 damit ausgefiihrte Versuche iiber die Temperatur-Stoff- 

 wechsel-Kurve von Insektenpuppen. " (Biocheni. Zeit- 

 schrift, 19 1 4.) 



August Krogh. " On the Rate of Development and CO2 Pro- 

 duction of ChrysaUdes of Tenebrio molitor at Different 

 Temperatures." (Zeitschrift f. allg. Physiologie, 1914.) 



August Krogh, " The Quantitative Relation between Tempera- 

 ture and Standard Metabolism in Animals." (Internal. 

 Zeitschrift f. pkysik-chem. Biologic, 1914.) 



Torbjern Gaarder. " Uber den Einfluss des Sauerstoffdruckes 

 auf den Stoffwechsel. " {Biochem. Zeitschrift, i, 1918.) 



Richard Ege, " On the Respiratory Function of the Air-stores 

 carried by some Aquatic Insects (Corixidae. Dytiscidrc. and 

 Notonecta). (Zeitschrift f. allg. Physiologie, 1915.) 



Reviews of Books 



WATER AND LIFE, AND OTHER MATTERS 



The Animal and its Environment. By L. A. Borrad.^ile, 

 Sc.D. (Henry Frowde and Hodder & Stoughton, 

 18s.) 



Dr. Borradaile has chosen so vast a subject that, as 

 he states in his preface, he " could do little more than 

 sketch the framework." This, however, he has clothed 

 with many illuminating details. He has shown great 

 skill and sound judgment in his choice of the various 

 aspects of the subject on which he writes. Out of 

 fourteen chapters, six deal with the fauna of the land, 

 the seas, and the fresh water, and these are particularly 

 well worth attention. He has an illuminating paragraph 

 on the part that water plays in the life and structure of 

 animals, ^^'illiam Watson has wxitten a verse : 



" Magnificent out of the dust we came, 

 .\nd abject from the sphere?." 



But I do not think the poet knew much about our origin. 

 As Dr. Borradaile says, " Water is the natural home of 

 all living beings, and there is no doubt that life started 



in it." Within the body it is of the utmost importance, 

 both as a constituent of protoplasm and as a circulating 

 medium. It is a great solvent. There is no other liquid 

 which dissolves such a number and variety of substances, 

 and, what is equally remarkable, is that on the great 

 majority of them it exercises no chemical action. With 

 the exception of mercury, it has a higher surface tension 

 than anjr other liquid, and this to some extent e.xplains 

 the mystery of the ascent of sap in trees. It also has the 

 highest specific heat of all liquid or solid substances under 

 ordinary conditions ; or, in other words, it requires more 

 heat to warm it to a given number of degrees than an 

 equal mass of any other matter. It is, further, trans- 

 parent, a matter of great importance to such animals 

 as have eyes, and to animals which are partly nourished 

 by the presence in their body of certain alga;. The 

 remarkable fact that the salinity of our body closely 

 approximates to the salinity of normal sea-water is shown 

 by the fact that living tissues, when removed from the 

 bod^^ are best kept alive when they are in a normal salt 

 solution ; and in cases of cholera, where water is being 

 poiured forth froni the body at an abnormal and amazing 

 rate, the injection of normal salt solution brings relief 

 and often effects a cure. The fact that even in the 

 mammalia the embryo possesses gill-slits and a fish-like 

 circulation and is surrounded by watery fluid is empha- 

 sised by Gibbon at the beginning of one of the six sketches 

 of Ms autobiography. He tells us that " after nine 

 months of an aqueous existence I was painfully trans- 

 ported to the outer world." 



Dr. Borradaile writes in a plain, straightforward style, 

 rather compressed owing to the magnitude of his task. 

 As an example of his clearness we may quote a paragraph 

 from his chapter on Parasitism : 



The relations between parasite and host vary 

 enormously, both in kind and in closeness, in different 

 cases. A parasitic organism is one which, living on 

 or in some other organism, and deriving food or 

 some other benefit from it, in some way harms it. 

 The benefit accruing to a parasite is nearly alwavs 

 nutriment, but it may also, or only, consist in 

 transport or shelter. The harm which it does 

 may consist in damage to tissues, abstraction of 

 nutriment, or the excretion of poisonous sub- 

 stances. The series of such cases ranges from 

 some which hardly differ from the pre^^ng of a 

 small animal upon a large one — there is no great 

 unlikeness, for instance, between the habits of a 

 mosquito and those of a flea — to internal parasitism 

 of the most intimate kind ; and from others that 

 are not unlike the harmless associations of organisms 

 which we shall presently describe as ' synoecv, ' to 

 the causing of fatal diseases." 



The book has almost an embarrassment of illustra- 

 tions ; so many, indeed, that it is impossible to place 

 them near the subject-matter. There are four good 

 coloured plates and 426 figures, whose reproduction 

 varies in merit. Some of them are distinctly poor. The 

 book is crowned by a most adequate index extending 

 over seventeen pages. Its price of iSs. is distinctly 

 moderate. 



A. E. Shipley. 



