January 19, 1922] 



NATURE 



87 



Wb have received the Report of the Bacteriological 



tion, State Board of Agriculture, U.S.A., for 1920. 



uch work has been done on the keeping qualities of 



ters, the decomposition of peat, silage production, 



vine infectious abortion, various fermentations, soil 



id food. For the isolation of the Bacillus abortus, 



le causative organism of infectious abortion, a liver 



ar medium is recommended with an addition of 



n 10,000 gentian violet. The medium should have 



a hvdrogen-ion concentration of between 6-6 and 



64, and the cultivation should be conducted in a 



closed chamber, in which 10 per cent, of the air is 



1^ replaced by carbon dioxide. 



^^^An account of the brachyuran crabs collected by 

 ^^He American Museum Congo Expedition has been 

 ^^Biblished recently by Miss Mary J. Rathbun (Bull, 

 ^^ftner. Mus. Nat. Hist., vol. 43, pp. 379-474, 30 plates). 

 ^^Blie collection contains about 3000 specimens belonging 

 to forty-three species, and the large series has enabled 

 the author to define many of the previously known 

 species with greater -accuracy. Three of the four 

 species of Callinectes known to occur on the West 

 African coast are well represented in the collection, and 

 details of their systematic characters are given. The 

 author states that the collection of land crabs (Cardi- 

 soma), about 120 specimens, serves to demonstrate 

 that certain differences between the African species, 

 Cardisoma armatum, and the American species, Cardi- 

 soma guanhumi, are constant. The river crabs 

 (Potamonidae) form the most important part of the 

 collection, and are represented by nine species, four 

 of which are new. Notes on the bionomics of these 

 crabs are added by Mr. H. Lang, leader of the ex- 

 pedition. 



The rodents of North America, prairie dogs, ground 

 squirrels, pocket gophers, jack-rabbits, field mice 

 and rats, are responsible for depredations amounting 

 to ioo,ooo,oooL a year to field crops, pasturage, and 

 stored products. Mr. W. B. Bell, in the Year-Book 

 of the United States Department of Agriculture for 



: 1920, gives an account of the damage which they 

 do, and of the measures taken to control or eradicate 

 them. The matter was first taken up by the Biological 

 Sun-ey, which devised means both of prevention and 

 cure. By their field operations and by demonstration 

 plots they were able to convince the farmer and stock- 

 man of the efficacy of their measures, and in this 

 way they won their co-o^jeration, as well as financial 

 support from the individual States of North America. 

 The work now comprises thoroughly organised aggres- 

 sive campaigns in sixteen of the Western States. The 



f two chief methods of control are poisoning by 

 strychnine and organised drives, and the methods of 

 prevention include the erection of rodent-proof fencing 

 and the introduction of rat-proof devices into buildings 

 used for storage purposes. Mr. Bell's account gives 

 a vivid idea of the menace which these rodents are 

 to the food supplies of North America, and the valu- 

 able results obtained by organised effort on a compre- 

 hensive scale for their control and eradication. The 

 menace is equally serious in this country, and the 

 NO. 2725, VOL. 109] 



measures adopted in America deserve the serious con- 

 sideration of the Government and local authorities 

 here. 



We have received an interesting letter from Mr. 

 J. Anderson, of Sewerby, near Bridlington, stating 

 that one of a fine group of the Chilean tree, Araucaria 

 itnbricata, at Sewerby House had produced a large 

 number of seeds from which healthy young plants 

 have been raised ; he asks if this is an unusual 

 occurrence. Mr. W. J. Bean, Royal Botanic Gardens, 

 Kew, informs us that this is not a rare occurrence, 

 and for many years past trees in various parts of the 

 country have borne fertile seeds. He remembers so 

 long ago as 1906 seeing self-sown young plants at 

 Castle Kennedy, in Wigtownshire, growing beneath 

 the trees from which the seeds had fallen. Similar 

 self-sown seedlings may be seen at Strathfieldsaye, the 

 seat of the Duke of Wellington ; and other places 

 where fertile seeds have been developed are Beauport, 

 Tortworth, CastlehiU, in North Devon, and Bicton, in 

 South Devon. Mr. Anderson also states that some 

 twenty-five or thirty years ago one of the trees "bled 

 to death " from a scar caused by the breaking away 

 of a branch. This also has been known to happen 

 before. A case is known where a tree died from a 

 running wound made at its base by the scythe of a 

 workman mowing the grass. Mr. Anderson, how- 

 ever, records an interesting fact that we do not 

 remember to have seen noted before : when the roots 

 of the dead tree were being removed the workmen 

 dug up large quantities of resin which had set into 

 hard, amber-like masses. The seeds are eaten by the 

 Araucanos and other Indian tribes in Chile. Mr. 

 H. J. Elwes, who visited the native forests of this 

 tree in 190 1-2, states that he has eaten them both 

 roasted and boiled and found them very palatable, 

 with a nutty flavour somewhat like that of almonds. 



Development of the petroleum resources in Alaska 

 has been, as we might have expected from the nature 

 of the country, an extremely slow and somewhat 

 costly matter ; the comparative inaccessibility of the 

 oil-bearing territory and the rigorous climatic condi- 

 tions have combined to retard progress to the point of 

 questioning the justification of a continuance of opera- 

 tions. The first well was brought in at Katalla in 

 1901, and was followed by a short-lived oil boom, 

 afterwards depressed by the wonderful results of Cali- 

 fornian development ; since that year forty wells have 

 been drilled in Alaska, thirty-one in the Katalla field 

 and the remainder in other prospects, including the 

 Iniskin Bay and Cold Bay districts; Yakataga, on 

 the Pacific seaboard, and Smith Bay, on the Arctic 

 coast, are mentioned as further areas where indica- 

 tions are good. The total production to date amounts 

 to some 56,000 barrels of crude oi! which has been 

 refined and used locally; the oil is of paraffin base, 

 of specific gravity varying from 41° to 45° (Baum^), 

 high in petrol, and with no sulphur content; it is 

 obtained from Tertiary beds the structure of which 

 is at present doubtful. Geological exploration is a 

 matter of great difficulty, and the results set forth 

 in the preliminary report on the country (U.S. Geol. 



