5Q 



NATURE 



[September 19, 1918 



cent, of all experiments were inoculations, or other 

 proceedings performed without anaesthetics. The 

 decrease in the number of experiments goes with the 

 fact that many of our pathologists and bacterioli 

 are working in one or other of the theatres 

 of war. Indeed, the war is writ large all over this 

 report. Of the twenty new places registered under 

 the Act, fourteen are military hospitals and labora- 

 torii s, mostly for Canada and New Zealand. Owing 

 to tie shortage of men for the work, women are help- 

 ing; of the 695 licensees, 43 were women. The number 

 of licensees is discounted bv the fact that no fewer 

 than 402 of the 695 mad. no use of their licences 

 during 1917. 



Reports have recently been received from various 

 quarters of the occurrence in rooms of myriads of 

 little black Hies. These not only swarm upon the 

 window-panes, but have also been found in drawers, 

 under carpets, and even behind the glass of framed 

 pictures. Specimens that have been submitted to the 

 xNatural History Museum, South Kensington, prove to 

 be Pteromalus deplanaius, Nees, a species belonging 

 to the parasitic Hymenopterous family Chalcididae. 

 There appears to be some uncertainty as to the host- 

 insect that gives rise to such swarms of the parasite. 

 The latter is recorded to have been bred from insects 

 of various orders, e.g. a moth (Tortrix xylosteana), a 

 beetle (Ceuthorrhynchtis asperulus), and a Cynipid gall 

 (Teras terminalis), but none of these hosts is likely 

 to be the source of origin of such swarms of the 

 parasite indoors; it is probable that in such circum- 

 stances it has emerged from one of the wood-boring 

 furniture beetles (Anobium striatum or Xestobium 

 tessellatum), though there is no definite record of such 

 an origin. Should this prove to be the fact, the 

 Pteromalus, though, perhaps, regarded bv the house- 

 holder as a nuisance, is evidently from its numbers a 

 useful and efficient check upon the insidious and 

 destructive pest of indoor woodwork, whether furni- 

 ture, wainscotting and panelling, or beams and floor- 

 boards. Information of the definite association of the 

 Pteromalus with one of these wood-boring beetles 

 would be welcomed bv the Natural History Museum. 



Mr. Cloudesley Brereton writes to us in regard 

 to the origin of water-snails and leeches in a small 

 artificial pool in a London garden. The basin, a few 

 square feet in size, was made about three years ago, 

 and one or two water-lilies were placed in it. Two 

 years later some water-snails appeared, and this year 

 three leeches. There is no pool of any sort in adjacent 

 gardens. The water comes from trie main. Where 

 have the animals come from? (a) They may have 

 been introduced in a young phase along with the 

 water-lilies. The spawn of Limnaea and some other 



fresh-v, ails is deposited on the under-surface of 



water-plants, and the eggs of some fresh-water leeches 

 are similarly attached. (6) Thev mav have been intro- 

 duced along with the main water— the snails in their 

 larval state, hes either when very small or 



later. On ^ two occasions we have obtained from a 

 house-tap in a large town leeches about 2 in. long. 

 (c) Even in transitory rain-water pools the sudden 

 appearance of fresh-water molluscs has been repeatedly 

 observed, and we do nol know that any circumstantial 

 explanation has been given. Tt is' probable that 

 water-birds, such as wagtails, mav occasionallv servo 

 as distributors. Darwin wrote In the "Origin of 

 Species" of just-hatched shells clinging to a duck's 

 foot, and Sir Charles Lyell told him of a water-beetle 



Dytiscus) which carried an ^ncvlu a fresh-water 

 snail like a minute limpet. Mr. Brereton's observa- 



ion, which has its counterpart in thi ience of 



deserves further investigation. 

 NO. 2551, VOL. I02] 



Entomologists are still in doubt as to the siage of 

 the life-histon in which the common house-fl) 

 normalh passes the winter. A paper on the subject 

 lias been lateh published in the Journal of Agricul- 

 tural Research (vol. \iii., No. 3) by R. H. Hutchi- 

 son, who concludes, from observations and experiments 

 made in Washington, that larvae and pupa; survive 

 the cold season in and under large manure-heaps, and 

 thai breeding ma) go on through the winter if flies 

 gain access to heated buildings, and find there both 

 food and material suitable for egg-laying. 



I in stone-flies (Perlidae) have hitherto been con- 

 sidered as of no economic importance except that 

 they serve as bait for anglers. A paper by E. J. 

 Newcomer (Journ. Agric. Research, vol. xiii., No. 1) 

 is therefore noteworthy, since it records damage to 

 orchard foliage by some species of Taeniopt. 1 



The " Summary of Progress of the 1 " 

 Survey of Great Britain for H117" (11. M. Stationery 

 Office, 1918, price 2s.) contains a number of valuable 

 facts relating to the modes of occurrence and probable 

 reserves of iron-ores in Great Britain. Mr. Lamplugh's 

 account of the oolitic ore of Jurassic age revealed by 

 the Dover coal-borings is especially noteworthy, a 

 reserve of about 100,000,000 tons being indicated. 

 Dr. R. Campbell describes Scotch occurrences of 

 potash-felspar. 



The issue of the American Journal of Science for 

 July, 1918, contains 416 pages, and commemorates the 

 one hundredth anniversary of the foundation of the 

 journal. The progress of the sciences since 1818 is 

 described in eleven chapters, and the entire cost of 

 the issue has been defrayed from the Silliman 

 memorial fund. In his review of the history of the 

 journal, Prof. E. S. Dana gives a facsimile of the 

 covering title of vol. i., No. 1, which shows that its 

 scope included "agriculture and the ornamental as 

 well as useful arts." The essay on " The Progress of 

 Historical Geology in North America," by Charles 

 Schuchert, contains important remarks on strati- 

 graphy, and the following classification is proposed 

 for the older Palaeozoic systems :■ — Taconic (Olenellus 

 beds), Cambrian, Champlain (Emmons, 1842) or 

 Ordovician, Silurian. The author does not seem 

 aware of Lapworth's support and revival of the term 

 Taconic in 1S01. Joseph Barrell, in a philosophic 

 article, reviews the growth of our knowledge of 

 earth-structure; and R. S. Lull deals with vertebrate 

 palaeontology, a subject to which the United States" 

 have made such paramount contributions. II. L. 

 Wells and H. W. Foote, in the article on chemistry, 

 furnish a table of the elements on Mendel^eff's 

 scheme, in which recent discoveries are included. 

 Attention is directed bv the authors to the remark- 

 able compartment in Group III., in which fourteen 

 metals of the rare earths are summarised as 

 "lanthanum 1300 to lutecium 174-0," the full list 

 being added below. The centurv's progress in physics 

 is reviewed by L. Page; but W. R. Coe deals onlv 

 with American developments in zoology. The capture 

 of Louis Agassiz for the United States in 1846 is 

 recorded with warm appreciation. 



Mr. J. T. Jutson (Proc. Row Soc. Victoria, 

 vol. x\x., part 2, 1918, p. 165) furnishes striking 

 examples of the influence of the crystallisation of 

 soluble salts in promoting rock-weathering in sub- 

 arid regions. He acknowledges bis indebtedness to 

 Prof. J. Walther, who directed attention to the sub- 

 ject during the visit of the British Association to 

 Australia in 1914. Level rock floors are developed 

 around lakes, where moisture, containing for the 

 most part sodium chloride, is drawn up bv capillarity. 

 The solidifying of the salt disintegrates the rock, and 



