Feb. lo, 1876] 



NATURE 



289 



lines, and works preparatory to bringing the new lands 



under culture. 



The interest on the above sum will raise it to 



\ 13,400,000/., but one-fourth of this will be granted as a 



subsidy by government, which will be amply compensated 



by the comparatively enormous addition to its small 



territor\-. 



Of the 473,000 acres to be drained, four-fifths, as we have 

 said, are of great value, composed as they are of a bed of 

 more than a metre thick of the most fertile mud deposited 

 for centuries by the Yssel and other rivers of which the 

 Zuyder Zee is the receptacle. Only one-fifth consists of 

 land of less value and of sands which will be useful in 

 constructing the base of the dike, or to establish large 

 reservoirs, indispensable in all drainage work, for the 

 reception of the waters until they can be conveyed to the 

 sea. Deduction being made for the land absorbed by 

 these works, by canals, dikes, roads, &c. &c., there will 

 remain upwards of 400,000 acres suitable for culture, and 

 the selling value of which ought considerably to exceed 

 the expenses of the enterprise. Every one must wish 

 that this bold and really beneficent scheme may be carried 

 out with complete success. 



THE BIRDS OF NORTH-EASTERN AFRICA ^ 



BARON THEODOR VON HEUGLIN is weU known 

 as one of the most active and successful of the 

 travellers and naturalists of Germany— one who may 

 fairly rank with the Wallaces and Bates of our own 

 country — as regards the extent of his researches. No 

 man living has devoted more time and toil to the inves- 

 tigation of the Fauna of North-eastern Africa, and as 

 regards the classes of birds and mammals, no man living 

 has a better acquaintance with them. Twelve years 

 passed on the coasts and islands of the Red Sea, in the 

 marshes and jungles of the WTiite Nile, and in the High- 

 lands of Abyssinia, during which time constant attention 

 was devoted to the observation and collection of animals 

 have given Herr von Heuglin unrivalled opportunities for 

 amassing this knowledge, to which his skill as an artist 

 has contributed additional facilities. Soon after returning 

 from his last jouiney in 1865, Herr von Heughn planned a 

 general work on the Ornithology of North-eastern Africa 

 to embrace all the notes and observations collected 

 during his different excursions, together with the infor- 

 mation acquired by the study of specimens from these 

 \ countries already existing in the continental museums. 

 ! In 1869, the first part of the present work was issued, but 

 I its large extent hindered its progress, and the author was 

 j called away to join the German Expeditions to Nova 

 : Zembla and the extreme north, to which he was attached 

 j as naturaUst. It was not, therefore, until the close of last 

 : year, or, we believe we may say until the beginning of the 

 ; present year, that the concluding part of the Ornithology 

 i of North-eastern Africa was issued from the press, 

 i Completed, it now forms four volumes, illustrated by 

 : fifty-one coloured plates and a map of the region of 

 which it treats, and is by far the most perfect work on 

 the subject hitherto published. Prior to the completion 

 of the present work Riippell's Atlas, and other publi- 

 cations were, so far as regards Nubia and Abyssinia, 

 the only works of reference, whilst of the district of 

 the White INile so fully explored by Von Heuglin, 

 ; rery little was known except from fragmentary no- 

 . tices. In the piesent extended work the ornithology 

 ' of the whole of these countries, together with that of 

 I Egypt, the Red Sea, and Northern Somali-land, are 

 ' treated of together. The sum of species of birds is thus 

 raised to a high figure, no less than 948, of which upwards 

 of 200 are entirely confined to North-eastern Africa. 

 European species are likewise numerous in these countries, 



" Omithologie Nordost-Afiika's, der Nilquellen iind Kusten-Gcbiete, 

 oes Rothen Meeres und des nordlichen Somal-Landes," Yon M. Th. Ton 

 ttenghn. In \ier Theilen. (Casscl : Fischer, 186^1874.) 



Northern Africa being, as is well known, the favoured 

 haunt of our summer migrants during the winter season. 

 Upwards of 300 European birds thus come to be included 

 in Herr von Heuglin's list. The plan of our author's 

 work is good, though it seems to be rather adapted for the 

 home student than for the field-naturalist, neither family 

 nor generic characters being included. But we observe with 

 pleasure that specific diagnoses are given in Latin to all 

 except the best known species, which, after the contumely 

 that certain imperfectly educated naturalists have recently 

 thought fit to bestow upon that classical tongue, is worthy 

 of all praise. The references to former authors are also 

 numerous, and, so far as we have been able to test them, 

 more accurate than is too often, unfortimately, the case in 

 works of this kind. But the great feature of the book are 

 the observations on the habits and localities extracted 

 from the note-books of the imwearied author. These are 

 much more numerous, and better put together than in 

 almost any other work on foreign ornithology with which we 

 are acquainted. Errors and omissions there are no doubt, 

 and must be, in a work of this magnitude, as indeed is 

 sufficiently evident by the many pages of additions and 

 corrections annexed to the fourth volume, but Herr von 

 HeugUn has spared no trouble to bring his Ornithology of 

 North-eastern Africa up to date, and his volumes will 

 long remain a standard work of reference upon the birds 

 of these districts, which are now attracting so much 

 attention in civilised Europe. P. L. S. 



FERTILISATION OF FLOWERS BY INSECTS^ 



XIII. 



Additional A Ipifu Flowers adapted to Cross-fertilisation 

 by Lepidoptera. 



THE same relation which I have shown to exist 

 between Daphne Mezereum and striata^ Primula 

 officinalis and villosa, Rhinanthtis crista-galli axid alt)inus 

 (Nature, vol. xi. p. no), exists also between Viola tri- 

 color* and calcarata, the former inhabiting the plain and 

 the lower mountainous localities, and being adapted to 

 cross-fertilisation by bees ; the latter, on the contrary, 

 inhabiting the higher Alpine regions, and being adapted 

 to fertilisation by butterflies. 



Viola calcarata is foimd in the Strela pass towards 

 Davos (2,300 metres above the sea-level), and in the rocky 

 slopes of Piz Umbrail towards Ouarta Cantoniera (2,600- 

 2,700 m.) in such plenty as to appear from some distance 

 like a blue carpet of flowers. In the latter locality, 

 July 15, 1875, I saw th?se flowers assiduously \asited by 

 different butterflies, of which I caught two specimens of 

 Colias phicomone., and three Erebia laprona E. (manto, 

 W. V.) The modifications of structure by which the 

 flowers of V. calcarata (Fig. 82-85) differ from those of 

 V. tricolor (Fig. 15-22, Nature, vol. ix., p. 46), besides 

 their eminent conspicuousness, so frequently found in 

 Alpine flowers, are such as prevent Diptera and probably 

 also Apidas from sucking the honey, whereas butterflies, 

 for which alone the honey is reserved, cannot suck it 

 without effecting cross-fertihsation. For the spur, which 

 generally is only 3-4 mm. long in V. tricolor, exceeds in 

 this species 10 mm. in length, its width being only i mm. 

 in the vertical, and scarcely half a millimetre in the hori- 

 zontal direction ; and the stigmatic knob, provided with a 

 labiated appendage, as in the large-flowered form of V. 

 tricolor, lies so closely pressed against the under lip, that 

 no proboscis of any butterfly can enter the spur without 

 grazing the stigmatic lip. The pollen-grains, when they 

 fall out of the anthers, collect in the hairs which clothe 

 the furrow of the under lip {po Fig. 85), and no proboscis 

 of a butterfly can be inserted into the spur without being 

 smeared with pollen-grains, which, in the flower next 



» Continued from voL xiii., p. 212. 



a Sec H. Muller, " Die Befruchtung der Blumen durch Insecten " Leipzig, 

 1873, p. 14s, and Nature, voL ix. p. 44, 



