May. 1913. 



KNOWLEDGE. 



187 



prominence in scientific literature. Professor Bryan has now 

 introduced the subject and has, moreover, invented a device 

 which improves the mechanical player in connection with its 

 " touch." The theories of Helmholtz and Kaufmann on the 

 action of the pianoforte are very incomplete and do not take 

 into account either the sounding board or the time and nature 

 of the impact of the striking keys. It is this last factor which 

 controls the quality of the tone given by the vibrating wire, 

 and the quality of the tone is regulated by the " touch " of 

 the pianist ; the problem is whether a mechanical player can 

 be devised which will be capable of adjustment so that its 

 touch can be modified. Professor Bryan, by means of a 

 lever which regulates the air pressure, has succeeded in 

 imitating mechanically to some degree the touch of the 

 human hand. Still, the touch and emphasis which can be 

 given by the hand to a single note amongst many others 

 within a number of chords is still a problem which it would 

 seem to be somewhat difficult to solve in a mechanical player. 



UNDAMPED OSCILLATIONS.— Electrical waves can 

 be produced either in a continuous train or as a succession 

 of damped vibrations, as with the oscillations produced for 

 the purpose of wireless telegraphy by means of the spark 

 discharge. The production of a continuous train of waves is 

 the type of oscillation which is employed by Poulsen in his 

 systems of wireless telegraphy and telephony. An oscillation 

 circuit of this type can be conveniently set up for laboratory 

 purposes in the following way, and it may be pointed out that 

 it is a very convenient method of obtaining discharges through 

 gases at low pressures, when it is not possible to use metallic 

 electrodes. 



An arc is constructed of copper and carbon, the carbon 

 is fitted in a brass tube, which passes air-tight through another 

 brass tube fitted through an indiarubber cork ; the carbon 

 can be rotated or moved in and out by rotating the brass 

 tube. The copper is screwed to the end of a brass tube 

 passing through a rubber cork, and down which passes an 

 iron tube through which water passes into the brass tube ; the 

 copper electrode can thus be cooled. The corks fit into the 

 ends of a silica tube, which is cooled by an outer tube, through 

 which water passes. The arc is connected through suitable 

 resistance, giving about two or three amperes, to the two 

 hundred volt mains. The arc is also connected to a variable 

 inductance — a coil of insulated wire wound on a wooden 

 frame, and so bared that a slider brings in more or less 

 inductance, and a variable condenser connected in series. If 

 a. large inductance and capacity, consisting of a long coil of 

 fine wire wound on a tall glass cylinder, is connected to one 

 end of the first inductance, electrical oscillations are set up 

 and are of sufficient intensity to illuminate vacuum tubes 

 situated several feet away. 



ZOOLOGY. 

 By Professor J. Arthur Thomson, M.A. 



UTILITY OF SENSITIVENESS TO LIGHT.— It is 

 well known that many animals are very sensitive to different 

 degrees of illumination — some seeking more light and others 

 less. Dr. V. Franz gives some good illustrations of the utility 

 of this sensitiveness. Many larvae hatched on the floor of 

 the sea make for the light, which is the best thing they can do 

 for nutritive and other reasons. Still more frequent is the 

 case of animals which show marked light-sensitiveness only 

 when some unusual conditions have intervened, such as per- 

 turbations in the water or foulness of water. They retreat in 

 the direction of the light conditions they are accustomed to. 

 They make for stronger or weaker light, as the case may be, 

 and the degree of illumination has a directing influence in a 

 sense. But it is not the degree of illumination in itself that is 

 significant ; it is the avoidance of concomitant unpropitious 

 conditions. 



MANGANESE IN ANIMALS.— It has been usuallv 

 supposed that traces of manganese detected in various 

 animals wore accidental and without physiological significance. 



But that is not the view taken by Messrs. Bertrand and 

 Medigreceanu, who have found manganese in dog, boar, pig, 

 ox, sheep, horse, rabbit, guinea-pig, seal, dolphin, fowl, duck, 

 angler, herring, and dogfish. It occurs everywhere in these 

 animals except in white of egg. There is great diversity in 

 amount, the maximum occurring in the oviduct of birds. 

 Liver and kidneys contain more than muscle or nerve. 

 There is a relatively large amount in hair, feathers, and 

 nails. The authors maintain that manganese must have 

 some physiological significance, probably as a catalytic agent. 



PERCHING IN BIRDS.— From the time of Borelli it has 

 been stated that the tendon of the ambiens muscle in many 

 birds is continued over the knee, and enters into connection 

 with the tendons of the perforati muscles which bend the 

 toes. When the knee is bent, the story runs, the ambiens 

 tendor is stretched, and through the mediation of the others, 

 clinches the toes on the branch. Professor Brauer points out 

 that the ambiens (which starts from the spina pubica) is 

 connected by its tendon with the tendon of the flexor of the 

 second or third toe, or with the third and fourth (which are 

 closely wrapped up together), but that it has nothing to do 

 with the bending of the first toe. In fact, its importance has 

 been greatly exaggerated. It has little effect in bending the 

 toes, and it is absent in many birds which ought theoretically 

 to have it. The bending of the toes is due to the perforati 

 muscles and the tightening of their tendons when the inter - 

 tarsal ankle joint is bent. 



REPRODUCTIVE DISHARMONY IN WILD DUCK.— 

 Julian S. Huxley calls attention to a remarkable "disharmony," 

 to use Metschnikoffs term, in the reproductive habits of the 

 wild duck (Anas boschas). The sexual appetite is extended 

 through the period of incubation. When the female is 

 actually on the nest this cannot be gratified ; hence, when a 

 female leaves her nest, she is often pursued by a number of 

 unsatisfied males. This may readily end in the drowning of 

 the overtaxed female. At Tring Reservoirs a considerable 

 number (probably seven to ten per cent.) of the females are 

 killed in this way every year. This is a noteworthy loss to 

 the species, due to a disharmony within itself. 



EXTRAORDINARY REGENERATIVE CAPACITY.— 

 E..Uhlenhuth removed the eyes and the surrounding skin 

 from the larvae of salamander and newt (Salamandra 

 maculosa and Triton alpestris), and implanted them in the 

 back of other larvae of the same species. The implanted eye 

 first underwent degeneration, and the visual cells disappeared. 

 But after some weeks there was regeneration, and the retina 

 showed the typical structure. The optic nerve grew, and with 

 the co-operation of the adjacent tissue, it formed a long strand, 

 which in certain conditions may grow into connection with a 

 spinal ganglion. 



A KING-CRAB ON THE SURFACE.— R. B. Seymour 

 Sewell reports from the "Investigator" the capture of an 

 adult king-crab (Limulus nioluccanus) in a large surface 

 tow-net, allowed to drift with the tide from an anchored 

 vessel, and kept on the surface by means of a bamboo float. 

 How an animal, so obviously a dweller on the floor of the sea, 

 had been carried or made its own way to the surface remains 

 a mystery. 



HABITS OF TRILOBITES.— Hans V. Staff and Hans 

 Reck have made an interesting and ingenious attempt to work 

 back to the habits of these ancient extinct types. They argue 

 from structural peculiarities to the mode of life. The primi- 

 tive Trilobites were creeping animals, and some retained this 

 habit. The Olenellus type illustrates adaptation to creeping. 

 But some, such as Phillipsia and Illaenus, became swimmers; 

 and some went further, like the laterally-expanded Deiphon- 

 Acidaspis types, becoming adapted to plankton-drifting. 

 Some, like Dalmanites, got long terminal spines suited for 

 creeping in the King-crab fashion. Some, which had pro- 

 gressed on the swimming line of evolution, relapsed and became 

 creeping types again. There is a fascination in this attempt 

 to put life into fossils, making them move about again each 

 after its kind. 



