646 



PHYSICS, PROGRESS OF. 



PHYSIOLOGY. 



springs, which could be remedied by heating them. 

 Holman (" Philosophical Magazine," December, 

 1895), in an article on galvanometer designs, con- 

 cludes that it is practically useless to wind turns 

 within a distance of about one quarter of the 

 needle length of the coil center, and that to in- 

 crease sensitiveness the needle must be as short as 

 is consistent with torsion of the suspending fiber. 



Magnetism. Magnetization. Grotrian (Wiede- 

 mann's " Annalen," April) has shown by induction 

 experiments made with coils of wire laid over an 

 iron sphere so as to cut off segments of various 

 sizes that the sphere is evenly magnetized through- 

 out, as theory requires. The direction of the grain 

 in wrought iron does not affect this result. Xa- 

 gaoka (Wiedemann's "Annalen." September) finds 

 that in fields of less than 20 C. G. S. units the mag- 

 netization of iron and amalgams shows a discon- 

 tinuity at the melting point. 



New Effect in a Field. Duane (Wiedemann's 

 " Annalen," July) finds that cylinders and disks of 

 glass, sulphur, paraffin, ebonite, or quartz, oscillat- 

 ing between the poles of a magnet with their axes 

 vertical and at right angles to the lines of force, 

 are damped proportionally to the intensity of the 

 field and to the speed of rotation. He regards this 

 as a hitherto unobserved magnetic effect, for his 

 experiments show that it is not due to action on 

 the suspending threads, to viscosity of the air, to 

 electrostatic effect from the coils, or to induction 

 currents in the substance. 



Hysteresis. I)u Bois and Jones (Berlin Physical 

 Society, April 14) have found by experiment that 

 hardening iron generally increases its hysteresis 

 and coercitive intensity, but decreases its residual 

 magnetism. Krupp's cast iron is distinguished by 

 low hysteresis and small coercitive intensity. 



Torsion due to a Solenoid. Moreau (Paris Acad- 

 emy of Sciences, May 26) finds that the increase of 

 torsion due to the action of a solenoid on a twisted 

 wire is proportional to the square of the magnetiz- 

 ing current, is independent of the wire's diameter 

 when this is small, and is always in the same sense 

 as the original torsion. 



Changes in Length. Chree (" Nature," Jan. 23) 

 calls attention to the fact that some recent authori- 

 ties assume that the " tractative force " of a magnet 

 acts continually within its mass as a force tending 

 to shorten it, while others, following older writers, 

 treat the same force as a tendency to lengthen the 

 bar. This has introduced confusion. 



Miscellany. Device for illustrating Laws of 

 Motion. Hrabowski (Wiedemann's "Annalen," 

 January) has devised a simple apparatus for illus- 

 trating all the laws of falling bodies. It consists 

 of a carriage that moves on a single rail and that 

 is pulled by a weight connected with it by a spring 

 moving in a vertical tube. The upper end of this 

 spring carries a pencil that marks on a vertical 

 plate as the carriage moves. When the carriage is 

 held still the spring is extended and the pencil 

 stops at a point that indicates the pull of the 

 weight. When the carriage is released the spring 

 contracts and the pencil traces a curve from which 

 can be seen the force that is acting at any moment. 

 By inclining the rail the phenomena of acceleration 

 and retardation may easily be studied. 



Cathetometer. Wadsworth (" American Journal 

 of Science," January) has invented a new form of 

 cathetometer in which the object to be measured is 

 compared with the standard scale by means of a 

 silvered mirror on a vertical axis just in front of 

 the objective. High accuracy and cheapness are 

 claimed for the instrument. 



Disturbance of Laboratories by Electric Roads. 

 Frolich (Berlin Physical Society, Jan. 17) finds 

 advantageous for the protection of physical labora- 



tories from the effect of electric railways the ar- 

 rangement of Siemens and Halske, consisting of 

 two coils of wire netting at right angles to each 

 other, stretched on a wire frame and surrounding 

 the instrument to be protected. By putting this in 

 contact with the conducting rail of the car line the 

 disturbance due to the passage of a car is compen- 

 sated and the effect on a magnetized needle is 

 much reduced. 



Odors. Gerardin and Nicloux (Paris Academy 

 of Sciences, April 27) suggest that the variation in 

 volume of air after treatment with a glowing plati- 

 num wire may be used to give a measure of bad 

 odors in air. 



PHYSIOLOGY. Respiration. The subject 

 of the respiratory exchange of the lower marine 

 animals, observes 11. A. Vernon, has an interest 

 quite apart from the mere measurement of the ex- 

 change of material taking place in particular indi- 

 vidual animals, because of the comparatively slight 

 differentiation the tissues have in many of them 

 undergone. In the higher animals the respiratory 

 exchange is the sum of the changes taking place in 

 various tissues which differ considerably from one 

 another in structure and chemical nature. The 

 respiration is also, as a rule, largely influenced and 

 governed by stimulation and inhibition from nerv- 

 ous centers. In animals such as Beroe and Cextns, 

 however, the nervous system is exceedingly primi- 

 tive, so that we are probably justified in looking 

 upon the respiratory exchange as almost entirely a 

 pure tissue metabolism phenomenon, uncomple- 

 mented by nervous influence. Now in the trans- 

 parent pelagic aniir.als, such as Medus'i, Cfr/ui- 

 phora, and SI/>u>. there appears to external ob- 

 servation but slight differentiation of the viscid 

 protoplasmic tissue, and so it seemed to the author 

 of interest to determine whether, within the limits 

 of experimental error, the unit weight of such ani- 

 mals has at the same temperature the same respira- 

 tory exchange, and whether the relation of the re- 

 spiratory activity to temperature is in the different 

 animals constant. The chief conclusions drawn by 

 the author from his experiments are that the re- 

 spiratory activity of lower marine animals, such as 

 the pelagic Ccelenterata. Tunicata, and Molhtscct, is 

 very small compared with that of the higher ani- 

 mals, such as the teleost fish ; that the respiratory 

 activity of different animals is very differently af- 

 fected by temperature as a rule, the less differen- 

 tiated and more Icwly the animal, the greater is the 

 effect produced ; that the respiratory activity is 

 very largely influenced by the size of the animal, 

 there being no valid exception to the general rule 

 that it varies inversely with the size. On keep- 

 ing animals in captivity the respiratory activity of 

 certain of them, as of the Medusa 1 , JUollusca, and 

 Vertebrata examined, either kept constant or slowly 

 diminished on certain days, while that of others of 

 them, such as Beroe, Cestus, and the Salpce, very 

 rapidly increased from day to day, although the 

 condition of the animals obviously deteriorated. 

 In pelagic animals the respiratory quotients as a 

 rule increase on successive days, but in the Verte- 

 brata examined they remained constant. Most of 

 the quotients are somewhat higher than those usu- 

 ally observed in warm-blooded animals. The trans- 

 parent pelagic animals contain a very small amount 

 of solid organic matter in their tissues. As a gen- 

 eral rule, for animals of the same class, it appears 

 that the respiratory activity depends on the mass of 

 the animal and on the amount of solid constituents 

 in its tissues. When kept in captivity pelagic ani- 

 mals diminish in size very rapidly. 



From observations to determine whether the 

 quantity of carbonic acid exhaled in breathing is 

 affected by the rarefaction of the air, made upon 



