524 



NATURE 



[Septemper 19, 1907 



and scientific hypotheses, it is necessary to distinguish 

 clearly betwoen hypothesis or theory and scientific observ- 

 ation. Let facts be accumulated in as great a measure 

 as possible, and theories too, in reasonable number, but 

 let us be quite clear as to what are facts and what are 

 theories, and quite definite in our ideas as to the relative 

 value of the two categories. Father Gerard and Dr. 

 Windle are justified in their remarks as to (he unscientific 

 character of much that is put forward in the name of 

 science, but without the authority of careful and accurate 

 observation. One reason for this is the attempt made to 

 instruct people in scientific progress who will not take the 

 trouble to understand the alphabet of nature. To the 

 general public a sensational assertion is much more 

 interesting than a plain statement of fact, and a personal 

 opinion is confused with the established truth to which 

 it refers. It is, however, a sign of progress that the 

 road to the present position of science is strewn with the 

 wreck of hypotheses and theories. No true philosopher 

 regards a hypothesis or theory as a Procrustean bed upon 

 which all new knowledge must be placed, but only as a 

 working or suggestive explanation of observed facts. In 

 this respect the scientific type of mind differs from that 

 which is content to accept mediaeval scholastic philosophy 

 as a final court of appeal for new learning. 



Biologisches Centralblatt for August 15 and September i 

 contains an article by Mr. A. Mordwiiko, of St. Peters- 

 burg University, on the biology of the Aphididse, being 

 a summary of a larger work on the same subject. The 

 reproduction of these insects is discussed in the first portion 

 of the article. 



In British Birds, No. 4, Messrs. Witherby and Tice- 

 hurst continue their account of important additions to the 

 list of species recorded from our islands since 1899. Atten- 

 tion may also be directed to a note by the first-named 

 writer on the nesting of a pair of herons in a pool on 

 Dungeness beach. 



The greater portion of the August issue of the Museums 

 Journal is devoted to the conference held at Dundee in 

 July last, where the presidential address was delivered by 

 Mr. J. Maclauchlan. The majority of the papers read 

 was devoted to subjects connected with art and manu- 

 factures rather than to natural science. 



Two papers in part iii. of vol. li. of the Memoirs and 

 Proceedings of the Manchester Literary and Philosophical 

 Society are devoted to zoological collections made by Mr. 

 S. A. Neave in N.E. Rhodesia. In the first, which is 

 illustrated by a coloured plate of two new species, the 

 collector discusses the birds, while in the second Mr. 

 G. A. Boulenger, who describes one new fish, records the 

 cold-blooded vertebrates obtained. 



The habits of the North American short-tailed shrew- 

 mouse (Blarina brcvicauda) form the subject of an article 

 by Mr. A. F. Shull in the August number of the American 

 Naturalist. In winter, at any rate, the species feeds 

 largely on snails of the genus Polygyra. These snails are 

 hoarded by the shrews for future use, the emptied shells 

 being either left on the surface of the ground or deposited 

 in various parts of the nests or burrows. Short-tailed 

 field-mice and vesper-mice are also attacked and killed for 

 food, while numbers of insects and earthworms are like- 

 wise consumed. The shrews are therefore highly beneficial 

 to the agriculturist. 



To the August number of the Zoologist Mr. Graham 

 Renshaw contributes some notes on the Californian condor 

 {Gymnogyps calif ornianus), a species in imminent danger 



of extermination. Although in former days ranging sa 

 far north as British Columbia, this condor — the largest 

 bird-of-prey in the United States — is now represented only 

 by a small remnant in south-west California. A flock of 

 twenty-six was, however, seen so lately as 1894, and it 

 is hoped that the species may still be holding its own 

 in the more remote mountains. A specimen is now living 

 in the Zoological Park, New York. 



Wh.\t amounts to little less than a revolution in the 

 taxonomy of invertebrates is proposed by Mr. R. T. 

 GiJnther in the August issue (vol. li., part iii.) of the 

 Quarterly Journal of Microscopical Science. Although 

 their moUuscan affinities were suggested by d'Orbigny in 

 1834, the arrow-w^orms (Sagitta, &c.) have been definitely 

 classed by nearly all modern zoologists among the annelids, 

 in which they constitute the group Ch^tognatha. Mr. 

 Giinther is, however, convinced that they are in reality 

 primitive molluscs. " No organ of importance," he re- 

 marks, " has been described in chaetognath anatomy which 

 is not paralleled by similar and, we believe, homologous 

 organs among the Mollusca. Indeed, we believe, we can 

 go further and demonstrate that the divergences of struc- 

 ture between the Chsetognatha and the Mollusca are 

 slighter than those known to exist between different orders 

 belonging to the latter phylum." The Mollusca, accord- 

 ing to the author, typically pass through a free-swimming 

 (" veliger ") stage, and while in creeping and sessile forms 

 the foot and shell attain high development, in pelagic 

 types the shell tends to disappear, and the foot may either 

 likewise atrophy or become modified into a swimming 

 organ. On this view the class may be divided into Necto- 

 malacia and Herpetomalacia, the former including the 

 shell-less Chaetognatha and the shelled Cephalopoda, and 

 the latter all the rest. 



In Nature Notes for September, Mr. O. C. Silverlock 

 records the results of experiments conducted by himself 

 during the last two years with the view of testing the 

 sensibility of ants to changes of temperature and to the 

 ultra-violet rays of the spectrum. As regards the first 

 point, the experiments indicate that very sinall changes of 

 temperature are perceived by these insects, the sensations 

 of heat in which must be much "more delicate than in 

 human beings. Many ants, for instance, perceive so small 

 a rise of temperature as o°3 C, while a very large per- 

 centage take cognisance of a rise of o°'5 C. In respect 

 to the ultra-violet rays, if has been already shown by 

 Lord Avebury that these affect ants like true light-rays, 

 and this being so, the author is of opinion that these rays 

 probably appear to them as a colour of which the human 

 mind cannot form a conception. The ants do not appear 

 to be chemically affected by these rays, but they change 

 their positions when placed in the spectrum by reason of 

 their dislike to the colour of these rays, and also on 

 account of the smaller heating effect produced by this 

 end of the spectrum. 



In the report for the year 1906-7 of the industrial section 

 of the Indian .Museum, Calcutta, Mr. I. H. Burkill 

 enumerates the additions to the collections received during 

 the year ; among the art specimens is a sword and silver 

 scabbard presented by the Tashi Lama. Of the pro- 

 ducts examined by Mr. D. Hooper in the laboratory, 

 the oleo-resin of Ilardwickia binata, the gum-resin of 

 Mangifera indica, and the oiL of Cochlospermum gossy- 

 pium are interesting ; also the sample of Kashmir hops. 



It was a happy inspiration to bring together in the 

 Natural History Museum at South Kensington a collection 

 of Linnean mementoes in commemoration of the biccn- 



NO. 1977, VOL. 76] 



