October i8, 1900] 



NATURE 



605 



depth in the channel before it enters the delta, in their natural 

 condition these channels are so shoal as only to afford sufficient 

 depth of water for the navigation of the smaller class of 

 steamers. About a quarter of a century ago Ciptain Eads 

 entered into a contract with the United States Government to 

 deepen one of these passes so as to give 27 feet at low water, 

 and to maintain this depth for a fixed period. Contrary to his 

 strong remonstrances the South Pass, the smallest of the three 

 outlets, was selected. Through this pass, by means of two 

 parallel training walls, the water was confined to a width of 

 700 feet, and by the scour thus created, aided to a large extent 

 by dredging, a channel having 26 feet at low water was made, 

 and has been maintained up to the present time. This contract 

 has now expired, and the dimensions of vessels in the meantime 

 having outgrown the channel, the Government have had to con- 

 sider the question of providing a deeper waterway. The Board 

 of Engineers to whom the matter has been referred have advised 

 that the South-west Pass should now be improved and deepened 

 so as to give a depth of 35 feet at loW water. 



The Board of Agriculture has published its annual report for 

 the year 1899-1900 on the distribution of grants for agricultural 

 education and research, with statements respecting the several 

 colleges and institutions allied and the experiments conducted. 

 The larger portion of the funds distributed in grants by the 

 Board consists of subventions of a general character awarded to 

 eight collegiate centres of agricultural education in England and 

 Wales. Subsidiary grants have also been made to three dairy 

 institutes, and in aid of the cost of certain specific experiments 

 undertaken under arrangement with the Board. Examinations 

 have also been conducted under the joint auspices of the Royal 

 Agricultural Society and the Highland and Agricultural Society 

 of Scotland for the recently established national diploma. 



Mr. Harold Wager reprints from ■Cn^ Journal ol the Lin- 

 nean Society an interesting paper on the eye-spot in Euglena. 

 He finds it to consist of a mass of pigment-granules apparently 

 imbedded in a protoplasmic matrix. The light absorbed by the 

 eye-spot seems to act upon a swelling near the base of the 

 flagellum, and thus to modify its movements. Euglena appears, 

 therefore, to possess a very simple form of light-organ, consisting 

 of a sensitive region — the swelling on the flagellum — and a 

 light-absorbing pigment-spot. 



In a note contributed to the Reniiconto of the Naples 

 Academy, vi. 5-7, Dr. Giuseppe de Lorenzo discusses the 

 probable causes of the increased activity of Vesuvius at the be- 

 ginning of May list. This activity assumed the form of 

 " Strombolian " explosions audible as far away as Posiiipo, by 

 which masses of incandescent lava were hurled into the air to an 

 altitude of about 500 metres. These explosions Dr. de Lorenzo 

 attributes to the exceptional rainfall, which, filtering through 

 the volcanic cone, has penetrated to the column of lava. This 

 hypothesis appears in conformity with the observations of 

 Spallanzani, von Rath, Dana and others, and with the experi- 

 mental researches of Daubree. 



Two papers on the figure of the earth have recently appeared, 

 one, by M. Marcel Brillouin, in the Revue ginerale Jes Sciences, 

 xiv., and the other, by Ingeguere Ottavio Zanotti Bianco, in the 

 Atti o( the Royal Academy of Turin, xxxi. M. Brillouin dis- 

 cusses the different geoidic surfaces adopted in the problem of 

 reduction to sea level, jand points out the relative advan- 

 tages of the geoids of Pratt and Helmert. Bianco's paper 

 contains extracts from the writings of Pratt and Helmert, 

 showing the relative part played by these investigators and by 

 Bruns in developing the general theory of geoidic surfaces. 



The Selborne Society's magazine. Nature Notes, contains in 

 its September issue an interesting account of a mirage, seen last 

 June over the Needles (Isle of Wight) from the opposite shore, 



NO. 1 6 16. VOL. 62] 



by Captain Giles A. Daubeny. It is not uncommon when look- 

 ing at a distant headland to see the appearance of a pointed 

 nose jutting out over the water— an effect caused by the forma- 

 tion of an inverted image near the water-line ; but in the present 

 instance four different horizons appear to have been observed 

 when viewing the rocks through a telescope. 



The admirable series of memoirs published by the U.S. 

 Department of Agriculture on the harmfulness or otherwise to the 

 agriculturist and horticulturist of the commoner birds of North 

 America has recently been augmented by one from the pen of 

 Mr. F. E. L. Beal, dealing with the food of the bobolink, black- 

 birds and grackles. This memoir forms Bulletin No. 13 of the 

 Department. The bobolink is an exception to most birds 

 in that, both at seed-time and harvest, it inflicts immense 

 damage on the rice-crops of the Southern States. At present, 

 therefore, the harm it does far outweighs such benefits as it may 

 confer ; but as the bird could exist perfectly well without touch- 

 ing a grain of rice, hopes are entertained that means may be 

 found of checking its depredations on that Crop. Oa the other 

 hand, most or all of the so-called blackbirds (which are not to 

 be confounded with the species of the same name in Europe) 

 feed largely upon noxious insects and weed -seeds, and are there- 

 fore highly beneficial to the cultivator. Much the same may be 

 said of the grackles. As usual, the Bulletin is illustrated with 

 good figures of the species described, and the whole publication 

 does the greatest credit to the Government by whom it is issued. 



Bulletin No 67 of the West Virginia University Experiment 

 Station is devoted to a communication by Dr. A. D. Hopkins 

 on the Hessian fly in West Virginia, and how to prevent losses 

 by its ravages. As the result of his investigations, the author 

 finds that the date of the appearance of the swarms of this 

 insect depends upon the latitude and altitude of the place, and 

 he gives a formula by means of which the former may be 

 approximately determined for any particular locality. From 

 this the dates may be calculated at which it is reasonably safe 

 to sow wheat in order to escape loss from the ravages of the 

 pest. The approximate limits of the best wheat-sowing period, 

 and also the approximate normals for the disappearance of the 

 fly in different districts, are graphically illustrated by means of 

 a map. 



The September issue of the American Naturalist commences 

 with an interesting paper, by Miss (or ? Mrs.) Sampson, on 

 unusual modes of development among frogs and toads. Com- 

 mencing with a rt'sumd of the normal mode of breeding as 

 exemplified in the common frog, the author goes on to show 

 how different members of the group depart from this mode of 

 procedure. Two species, for example, the one from West 

 Africa and the other from Brazil, deposit their spawn in ne.sts 

 formed of leaves stuck together, the tadpoles moving in a mass 

 of froth, recalling that of the cuckoo-spit insect. In both these 

 instances the spawn is deposited in the neighbourhood of water, 

 into which the tadpoles ultimately fall ; but in a tree-frog from 

 Rio, in which the eggs are likewise hatched in a frothy mass 

 among leaves, the larvae actually die if they are put into water. 

 In another Brazilian tree-frog the tadpoles frequent cracks in 

 rocks, and adhere to the surfaces of the latter by means of an 

 abdominal sucker. Full reference is made to the mode of 

 development in the Surinam toad, and also to that of the mar- 

 supial frogs, in which the young are hatched in a dorsal pouch. 

 But perhaps the most extraordinary "nursery" arrangements in 

 the entire group are those of the Chilian Rhinoderma, in which 

 the tadpoles undergo their development in an enormous pouch 

 on the throat of the male. In the same journal Mr. F. Russell 

 has a paper on cranial abnormalities in the American races, 

 among some of whom the persistence of the frontal suture may 

 occur as frequently as 29 per cent. 



