March 23, 1922] 



NA TURE 



39: 



must have occurred during the elevation of the 

 Andean ranges ; at such a time a water communica- 

 tion mav have been estabhshed between the two 

 oceans and the fruits of a Polynesian Pritchardia 

 deposited on an island in the Caribbean Sea. 



The fruits, which are plum-like in structure, but 

 with comparatively little flesh, vary in the different 

 species from the size of a large pea to that of a date. 

 The smaller ones would attract pigeons, which, though 

 now unknown in Hawaii, may at some time, when 

 greater land connections existed between the remoter 

 islands of eastern Polynesia and those of Papuasia 



and western Polynesia, have contributed to stock the 

 islands of the Hawaian group. But there is still the 

 difficulty of explaining the presence of large-fruited 

 Pritchardias on the most inaccessible summits of the 

 mountains of Hawaii. Prof. Beccari suggests that 

 these represent a surviving element of the vegetation 

 which covered the plains before the cataclysms wiiich 

 resulted in the elevation of the present mountains 

 and broke into fragments the originally much more 

 extensive land area. The monograph is illustrated 

 by twenty-four plates, mainly reproductions of 

 photographs taken by Prof. Rock. 



Agricultural Experiments at Ithaca, N.Y. 



THE Report of the Agricultural Experiment 

 Station of Ithaca, N.Y., for 191 9 contains a 

 number of memoirs of considerable interest, especially 

 from the botanical and entomological points of view. 



Work on the stimulation of growth by various 

 chemical compounds indicates that treatment with 

 potassium permanganate may result in a very marked 

 increase in the root-growth of various woody cuttings. 

 Other compounds of manganese, iron, and boron may 

 show at times a slight stimulating effect, but nutrient 

 solutions are, as a rule, injurious to the root-growth 

 of cuttings. In another paper the effect of man- 

 ganese compounds on soils and plants is discussed. 

 The general conclusion reached is that with wheat, 

 manganese salts presented in high concentrations 

 exert a toxic effect, but in lower concentrations a 

 marked stimulation is observable. When added to 

 soil, manganese salts were found to form manganese 

 dioxide in proportion to the basicity of the soil and 

 to develop a power to oxidise organic matter. 



In genetics two papers deal with chlorophyll 

 inheritance and aleurone colour in maize, and another 

 with the weak awn in certain Avena crosses. In 

 some crosses of awned and awnless varieties (as Burt 

 and Sixty Day) there is an almost complete domfnance 

 of the awnless condition, the factor for awning being 

 apparently prevented from operating by an inhibi- 

 tion which is closely linked with the factor for yellow 

 colour in the variety concerned. Environment seems 

 to affect the production of awns, and observations 

 suggest that an increase in the moisture-content of 

 the soil and of its organic matter and nitrogen tends 

 to decrease the number of awns. 



Soil conditions are dealt with in memoirs on the 

 translocation of calcium and on the reversibility of 

 the colloidal condition of soils. In the first case it 

 was found that the translocation of calcium through 

 a clayey silt loam soil with a rather large lime require- 

 ment is extremely slow, since in the experiment no 

 upward or downward movement of this element was 

 perceptible twelve months after various amounts of 

 calcium salts had been applied to the soil. In the 

 second case it was demonstrated that drying a surface 

 soil once produces as much effect in the colloidal 



material as repeated dryings alternated with moisten- 

 ings, the drying producing a change in the colloidal 

 material from which it does not immediately recover 

 on being wetted. The drying indirectly affects the 

 reversibiUty of its colloidal condition, the change being 

 directly produced through biological and chemical 

 action. 



On the bacteriological side attention is directed 

 to the effect of low temperature on soil bacteria and 

 to the number and types of bacteria found in ice- 

 cream during storage. In the soil there appears to 

 be no change in the bacterial flora due to freezing, 

 the bacterial activities being influenced only in so 

 far as the physical properties of the soil are affected. 

 The concentration of the medium, the length of time 

 of exposure, and the degree of cold are the three 

 important factors that determine the power of 

 resistance of the bacteria to low temperature. The 

 death of the bacterial cell when exposed to low 

 temperatiire seems to be due to the withdrawal of 

 water from the semi-permeable membrane or outer 

 layer of the cell. 



An outhne is given of the life-histories and methods 

 of control of various insects injurious to the hop in 

 New York, special attention being devoted to the hop 

 grub {Gortyna hnmanis, Guenee) and the hop redbug 

 [Paracalocoris Hawleyi, Knight). The hop grub 

 causes considerable financial loss, and in years when 

 the insects are plentiful they may cause an almost 

 total loss to some growers. The larvae damage various 

 parts of the vine, working in the buds, stem, and 

 roots, thus weakening the plants in various ways. 

 For control, clean cultivation is advised, with a 

 ploughed border several yards wide round the field. 

 The use of carbon bisulphide as an insecticide is 

 unsatisfactory, but paradichlorobenzine has been 

 successful when added to the soil of each hill in May. 



The plant-lice injuring the foliage and fruit of the 

 apple ( Aphis pomi, de Geer, A . sorbi, Kaltenbach, and 

 A. avencs, Fab.) are described and fully illustrated, 

 and the first part of a detailed systematic account of 

 the crane-flies of New York is issued, dealing with 

 the distribution and taxonomy of the adult flies. 



W. E. B. 



A' 



T a meeting of the Royal Anthropological 

 Institute held on March 14, Dr. W. H. R. 

 ]\ivers, president, in the chair, Mr. J. P. Mills, of the 

 Indian Civil Service, read a paper on the Lhota 

 Nagas of Assam. He said that in spite of its long 

 contact with the plains of Assam, this tribe has 

 retained its primitive dress and customs. It occupies 

 a portion of the Naga Hills lying to the S.E. of the 

 Brahmaputra Valley, and numbers some 18,000 souls. 

 Like the Angamis, the Lhotas trace their origin to a 

 mythical hole in the earth near the Kezakenoma 

 stone. In dress they resemble closely their neigh- 

 bours, the Aos, the men wearing a small apron and 



The Lhota Nagas. 



body cloths of various patterns, and the women a 

 small skirt of very dark blue, with a light blue median 

 band. Warriors in full dress wear human hair tails, 

 elaborate baldricks with fringes of goat's hair dyed 

 scarlet, and bear's hair wigs ornamented with hornbill 

 feathers. 



The villages, which are permanent, may contain any 

 number up to 300 houses and are built on the tops of 

 the ridges. The highest is at about 5000 feet. Each 

 village contains one or more " bachelors' halls " in 

 which boys and unmarried men sleep. In the middle 

 of the village stands the head-tree, usually a ficus, on 

 which heads taken in war were hung. Under it are 



NO. 2734, VOL. 109] 



