320 



NATURE 



[March 9, 1922 



division in this multinucleate organism is not syn- 

 chronous ; one nucleus is usually stimulated to divide 

 before the others, and this division is, for the time, 

 sufhcient to re-estabUsh the normal relations between 

 nuclei and C3rtoplasm. 



Variations in Organs of Aurelia. — It has long 

 been known that considerable variation occurs in 

 the number of radial canals and tentaculocysts in 

 Aurelia, but only recently has investigation been 

 made as to whether the ephyrae produced by individual 

 strobilae were always normal, or, if abnormal, were 

 similar in their abnormalities. Mr. J. W. Low has 

 pubhshed (Proc. Roy. Phys. Soc. Edinburgh, vol. 20, 

 pp. 226-35) ^'^ account of his observations on twenty- 

 seven productive strobilae, each of which was kept in 

 sea-water in a separate vessel. The ephyrae were 

 examined in the order in which they were produced. 

 The largest number of ephyrae given off by one 

 strobila was twenty-eight ; the average production 

 per strobila was about ten, and the total number of 

 ephyrae examined was 278, of which 90 showed major 

 or minor abnormalities. Six of the strobilae produced 

 only normal ephyrae having the usual eight arms 

 and tentaculocysts, four pairs of gastric filaments, 

 and four mouth-lappets. The remaining strobilae 

 produced ephyrae some or all of which exhibited 

 departures from the normal. The same strobila 

 may give rise to normal ephyrae and to ephyrae having 

 more or less than the normal number of arms, and in 

 particular cases there was found to be abrupt dis- 

 continuity, e.g. from a four-rayed to a twelve-rayed 

 form. The extremes of variation were represented 

 by three-rayed and fourteen-rayed examples. 



Microscope Objectives. — The problem of im- 

 proving the design of microscope objectives in the 

 near future has been taken up seriously in the last 

 few months, and three suggestions have been made 

 for the more accurate measurement of the errors to 

 which such objectives are subject. It is rightly felt 

 that better methods of testing must be introduced 

 before the objectives themselves can be improved. 

 Mr. Martin at the November meeting of the Optical 

 Society suggested a modification of the Hartman 

 test by transmitting the beam from the objective 

 through separate small holes in a screen ; Mr. Twyman 

 in the November number of the Philosophical 

 Magazine suggested a modification of his interference 

 method, and Dr. Hartridge in October showed to 

 the Cambridge Philosophical Society the curves he 

 had obtained by a third method. He restricts the 

 beam entering the objective to a small area and 

 determines by means of a micrometer the lateral 

 change of position of the image of a small object. 

 The change is reduced to unit magnification and 

 plotted against the portion of the aperture used, 

 expressed as a fraction of the numerical aperture 

 of the objective. The shape of the curve obtained 

 gives the curvature of the field, and the magnitude 

 of the spherical and chromatic aberrations present. 



Treatment of Surra in Camels. — Antimony salts 

 such as tartar emetic are frequently curative for 

 diseases caused by protozoal and other animal 

 parasites, e.g. in oriental sore and kala-azar caused 

 by Leishmania, bilharziasis caused by a fluke (Schisto- 

 somum), etc. Capt. H. E. Cross finds that injections 

 of tartar emetic cures camels affected with surra, a 

 disease caused by a trypanosome. Different methods 

 of administration were tried, and of 51 animals 

 treated, 31 were cured (Dept. of Agriculture, Punjab, 

 Veter. Bull. No. 2 of 1920). 



NO. 2732, VOL. 109] 



Enzyme Action and X-Rays. — In the Archives 

 of Radiology and Electrotherapy for January (No. 

 258) Mr. R. D. Lawrence records experiments on 

 the effect of X-rays on enzyme action. The diastatic 

 ferment of human blood and urine was chosen for 

 the investigation. Radiation was performed with a 

 Coolidge tube at 9 inches from the anticathode, with 

 a 5|-inch gap and unfiltered radiation at 2 milliam- 

 peres in the secondary. The radiation was carried 

 out for from i minute up to 20 minutes. In no 

 case had the radiation any effect on the enzyme 

 action. 



Anti-Oxidation. — During the study of the changes 

 undergone by acrolein on long standing, it was noted 

 by C. Moureu and C. Dufraisse that the spontaneous 

 oxidation of this substance by an " Autoxidation " 

 was influenced in a very marked manner by traces of 

 impurities. Further investigation of this process 

 [Comptes rendus, January 30) led to the unexpected 

 discovery that the autoxidation of a large number of 

 substances is prevented by the presence of certain 

 bodies, named by the authors anti-oxidisets (anti- 

 oxygenes), and this property is connected with the 

 presence of the phenol group. Thus, the oxidation 

 of benzaldehyde is prevented by the addition of a 

 twenty-thousandth part of hydroquinone. Hydro- 

 quinone, pyrocatechol, and pyrogallol are especially 

 active in preventing oxidation ; ordinary phenol, 

 resorcinol, guaiacol and the naphthols also act as 

 anti-oxidisers, but the proportions required differ in 

 each case. As an exception, phloroglucinol is with- 

 out action, and in this connection it is recalled that 

 phloroglucinol often reacts as a ketone. In the pres- 

 ence of a suitable proportion of an anti-oxidiser, fur- 

 furol remains colourless, acrolein gives no precipitate 

 of disacryl, styrolene gives no resin on standing, lin- 

 seed oil exposed in thin layers X^ ^-ir retains its 

 fluidity for three years, fats (including butter) do not 

 go rancid. Mineral substances, such as sodium sul- 

 phite and hyposulphite, are sensitive to the action 

 of anti-oxidisers. The authors also consider the bear- 

 ing of these facts on biology : phenols are fairly 

 common in plants, generally absent in animals. It 

 was found that the action of haemoglobin was not 

 affected by phenolic anti-oxidisers. 



The Effect of Moisture Content upon the 

 Expansion of Concrete. — Bulletin No. 126 of the 

 University of Illinois contains the results of a series of 

 experiments upon the expansion of concrete carried 

 out by Mr. T. Matsumoto, who has had some years 

 of experience on harbour works at Formosa. The 

 temperature coefficient of expansion of concrete is 

 about the same as that of steel, so that these materials 

 expand or contract together on heating or cooling. 

 Concrete expands when it absorbs moisture and con- 

 tracts when it is dried ; the contraction causes stress 

 in the concrete unless it is permitted to take place 

 freely, and this stress appears to be not as small as 

 is generally supposed. In reinforced concrete, the 

 contraction may set up stresses in the steel which 

 may reach the usually accepted working stress of steel 

 when the reinforcement is less than 1-5 per cent. 

 With 1:2:4 concrete and reinforcement greater than 

 1-5 per cent., shrinkage may produce stresses in the 

 concrete approximating to its ultimate tensile strength, 

 and such concrete is liable to develop cracks unless 

 proper provision is made. The author does not con- 

 sider that reinforced concrete is likely to be a durable 

 material in places where a corrosive influence on steel, 

 such as sea air, is active, unless proper protection 

 against shrinkage cracks is made. 



