FRAGMENTS OF SCIENCE. 



427 



planet D Q, however, discovered by Herr 

 Witt, of the Urania Observatory, of Berlin, on 

 August 13 th last, has aroused from the first 

 special attention through its remarkable be- 

 havior. The orbit is a very unusual one. 

 Mars has always been considered our nearest 

 neighbor, although it was known that some 

 of the minor planets were slightly nearer to 

 the sun when at perihelion than Mars is when 

 at aphelion. But the mean distances of the 

 latter were in all cases much greater than 

 that of Mars ; while that found for the new 

 planet is only 1.46 as compared with 1.52 

 for Mars, and, as the eccentricity amounts to 

 0.23, the perihelion distance is only 1.13, 

 and the least distance from the earth's orbit 

 only 0.15 as compared with 0.27 for Venus 

 in transit, and 0.38 for Mars in perihelion. 

 The planet will thus be far closer to us than 

 any other member of the solar system, and 

 will afford a most excellent means of deter- 

 mining the sun's parallax. Its diameter is 

 thought to be about seventeen miles. 



Extra-Organic Factors of Evolution. — 



Observing that our civilization has made ad- 

 vances or " strides " in recent years out of 

 all proportion to any improvements that have 

 taken place in our organic faculties, Arthur 

 Allin has insisted, in Science, on the im- 

 portance of extra organic factors in human 

 development. Our sense and motor organs, 

 he says, are essentially instruments and tools, 

 and so is the brain; and most if not all of 

 the three hundred or more mechanical move- 

 ments known in the arts are found exempli- 

 fied in the human body. Our sense organs 

 are thus indefinitely multiplied and extended 

 by such extra-organic sense organs as the mi- 

 croscope, telescope, resonator, telephone, tele- 

 graph, thermometer, etc. Our motor organs 

 are multiplied by such agencies as steam 

 and electrical machines, etc., in the same 

 manner. " The printing press is an extra- 

 organic memory far more lasting and durable 

 than the plastic but fickle brain. Fire pro- 

 vides man with a second digestive apparatus 

 by means of which hard and stringy roots 

 and other materials for food are rendered 

 digestible and poisonous roots and herbs 

 innocuous. Tools, traps, weapons, etc., are 

 but extensions of bodily contrivances. Cloth- 

 ing, unlike the fur or layer of blubber of the 

 lower animals, becomes a part of the organ- 



ism at will. One finds himself more or less 

 independent of seasons, climates, and geo- 

 graphical restrictions. By organic heredity 

 or the transmission of the congenital char- 

 acteristics of the parents to the children, 

 working alone, all progress depends upon 

 the transmission of variations occurring 

 within the organism. " Moreover, these ad- 

 vantageous organic variations die with the 

 individual, and must be born again, so to 

 speak, with each new individual." This 

 requires time, and progress depending on it 

 would be indefinitely protracted. On the 

 other hand, by means of social heredity, each 

 new member of the race has handed to him 

 at birth the accumulated organic advanta- 

 geous variations of sense and motor organs, 

 and the extra-organic adaptations that have 

 multiplied so indefinitely in the age of civ- 

 ilized man. " The vast importance of accu- 

 mulation of capital is obvious." 



Fossils as Criterions of Geological Ages. 

 — Prof. 0. C. Marsh said in a paper on The 

 Comparative Value of Different Kinds of 

 Fossils in determining Geological Age, which 

 was read at the meeting of the British Asso- 

 ciation, that the value of all fossils as evi- 

 dence of geological age depends mainly upon 

 their degree of specialization. In inverte- 

 brates, for example, a lingula from the Cam- 

 brian has reached a definite point of devel- 

 opment from some earlier ancestor. One 

 from the Silurian or Devonian, or even a 

 later formation, shows, however, little ad- 

 vance. Even recent forms of the same or 

 an allied genus have no distinctive charac- 

 ters sufficiently important to mark geological 

 horizons. With ammonites the case is en- 

 tirely different. From the earliest appear- 

 ance of the family the members were con- 

 stantly changing. The trilobites show a 

 group of invertebrates ever subject to modi- 

 fication, from the earliest known forms in 

 the Cambrian to the last survivors in the 

 Permian. They are thus especially fitted to 

 aid the geologist, as each has distinctive fea- 

 tures and an abiding place of its own in 

 geological time. In the fresh-water forms 

 of mollusca — the Unios, for example — there 

 is little evidence of change from the palaeo- 

 zoic forms to those still living, and we can 

 therefore expect little assistance from them 

 in noticing the succeeding periods during 



