and fanatical section of the Moslem population.

*

Such, briefly noted, are the chief conditions of slavery in Egypt. How widely they differ from those of the institution whose horrors fired our English abolitionists in the beginning of the present century, and twenty years ago thrilled both Europe and America in the pages of Uncle Tom's Cabin, need not be repeated. The one is, in short, simply domestic servitude under practically efficient guarantees against ill-treatment, while the other was the cruellest form of tyranny that man ever exercised over his fellow. But the two systems have this in common-that the same initial cruelties are and were necessary to feed both. This is not so, of course, as regards the white slaves, who are freely sold by their parents, and are themselves consenting parties to the bargain. In their case only the ethical sentiment of Christian, as opposed to Mohammedan, civilisation is offended; and an apologist of the institution might plausibly enough contend that this incident of it is vastly less immoral than the promiscuous 'social evil' which, while sternly reprobated by Moslem law and public feeling, flourishes under police license and almost with social sanction in Europe. It is different, however, with the more numerous class of black slaves, the victims of organised kidnappings and petty tribal wars as cruel as any ever waged on the West Coast; and the sufferings of these it is, during their capture and till they reach the Nile, which condemn even the mild domestic servitude that must be supplied at this price as absolutely as the brutal exaggeration of it which fifty years ago cursed our own colonies and the United States. If the class were selfrecruiting the case would be very different; but dependent as it is on barbarities. to which every African traveller, from Bruce to Schweinfurth, has borne wit

It must be borne in mind that it is a mild and harmless traffic as compared with slave-trading in other parts of Africa, and that domestic slavery in Egypt presents few of the horrible features which have been witnessed in other parts of the world.-Report of Mr. Beardsley, U. S. Consul-General at Cairo (1873).

ness, civilisation pronounces against it the same fiat of extinction that abolished slavery in the West. Egypt, it is true, is only in part answerable for these atrocities in the remote interior, the spoils of which find markets equally at Zanzibar, in the Hedjaz, in Tripoli, Tunis, Morocco, and Constantinople; but her share in the responsibility is still heavy enough to furnish unfriendly critics with a plausible argument against Egyptian civilization, and the credit of the Cairo Government is therefore directly staked on the complete suppression of this traffic. That the Khedive is fully sensible of this is shown by the efforts he has already made to reduce it to the narrowest limits; and, having done this, his determination to put an end to it altogether may be inferred from the enlarged powers he has conferred on Colonel Gordon to crush it everywhere between the First Cataract and the Equator. No ruler of Egypt could do more than entrust such a commission to such a man.* But even with Gordon Pasha in the Soudan, and the Khedive in Cairo, the suppression of the trade and of the institution it keeps alive must needs be slow. Custom and religion have too long consecrated both for any human power to at once stamp out either. With the gradual suppression, however, of slave-hunting and selling in Darfour and along the Upper Nile black slave-holding in Egypt proper must perforce die out; and with the withering of that main trunk of the institution the rest will speedily disappear. In the mean time, while this social revolution is being effected, Egyptian legislation and public sentiment may be fairly credited with having minimised the evils which are inseparable from slavery even in its mildest form.-Fraser's Magazine.

In a recently published letter on the subject of his new commission Col. Gordon says: I am astounded at the powers he [the Khedive] has placed in my hands. With the Governor-Generalship of the Soudan, it will be my fault if slavery does not cease, and if these vast countries are not open to the world. So there is an end of slavery, if God wills, for the whole secret of the matter is in the government of the Soudan, and if the man who holds that government is against it, it must cease.'

MANY years ago an ingenious tale appeared in one of the magazines, the hero of which had a theory to the effect that the last object seen by a dying person was imprinted on the retina, and could, by suitable means, be photographed, and so preserved. His researches on this subject and his final success were detailed with great appearance of truth, and in the end he discovered the murderer of his sister by recognizing in a chance-met stranger the original of the portrait he had, years before, obtained from the eye of the victim. It is curious how prophetic this seemingly wild fable has turned out to be of a wonderful discovery made within the last few weeks.

A short time since Franz Boll observed that the retinas of all animals, instead of being white or greyish, as was supposed, were of a beautiful purple-red hue. Boll supposed that this color was destroyed during life by strong light and restored by darkness, and that it invariably disappeared, for ever, a few seconds after death.

Since the publication of Boll's results, the subject has been investigated in great detail by Kühne,* who has arrived at conclusions the importance of which can hardly be too highly estimated. He found, first of all, that although the sightpurple (Sehpurpur) disappears within half a minute after death in bright sunlight, yet that in gaslight it remains unaltered for twenty to thirty minutes, and in the dark, or when exposed only to the yellow light of the sodium flame, for twenty-four to forty-eight hours after the time in fact, at which decomposition has set in. The color, moreover, exists only in the layer of rods and cones, and although discharged by high temperature and by certain reagents, it remains unaffected by others, such as common salt, alum, and glycerine, and is also unaltered when the retina is spread on a glass plate-of course, in yellow light-and allowed to undergo complete desiccation. Furthermore, when a retina was spread out on glass partly covered

*Zur Photochemie der Netzhaut. Gelesen in der Sitzung des naturhistorischmedicinischen Vereins zu Heidelberg den 5 Januar, 1877.

by strips of tinfoil, and then exposed to light, it was found that the otherwise bleached membrane retained its beautiful purple color wherever it had been protected from the action of light by the tinfoil. In other words, there was impressed upon it a positive photograph of the strips. It was now necessary to decide the question, How is the sight-purple renewed in the living animal after being bleached by light? The retina from one eye of a frog was removed and placed on a glass plate; an equatorial section was made of the other eye, and its posterior half was exposed to light, under the same conditions as the removed retina, until the latter was completely bleached. The second retina, still in its natural relations to the other coats of the eye, but presumably with its color discharged, was then taken to the sodium chamber, removed, placed on glass, and again brought into ordinary daylight. The purple color was found to be perfectly restored. From another eye the retina was removed in such a way that some black fibres of the underlying choroid coat still adhered to it; it was then spread out on glass and exposed to light. The bleaching effect was less marked when the choroid was left. Still more instructive is an experiment in which a portion of the retina was removed from its natural position until bleached, and then carefully put back, so as to be once more in contact with the choroid; when removed after a few minutes it was found that the sight-purple was completely renewed. It is thus proved that the restoration of the sensitive pigment is the special function of the choroid, the hexagonal cells of which, extending for a short distance between the rods and cones, continually sensitize the latter, as they become bleached by light. It follows from this that, as Kühne observes in a subsequent paper,* normal vision is only possible while a constant balance exists between the bleaching of the rods by light and the purpurogenous action of the retinal epithelium.

Vorläufige Mittheilung tiber optographische Versuche.' Centralblatt für die med. Wissenschaften, 1877, No. 3.

If, therefore, this balance were destroyed by a prolonged exposure to light, it should be possible to obtain a permanent optograph of a luminous object; and this Kühne now set himself to accomplish, devoting his attention to the eyes of mammals, in which the purple-forming function of the choroid ceases a few minutes after death.

A rabbit was fixed at a short distance (15 metre) from a square hole, of 30 centimetres in the side, in a windowshutter; its head was covered for a short interval with a black cloth, the cloth was removed, and the eye exposed to the light of midday for three minutes. The animal was then instantly beheaded, the eye removed in a chamber lighted by the sodium flame, and placed in a solution of alum. On the second day the retina was removed, and was found to exhibit, on a rose-red ground, a white image about one square millimetre in size, almost quadrate in shape, and with its edges sharp as if drawn by a ruler!

Naturally Kühne was not satisfied with this single experiment, decisive as it was, but a week after its publication brought out a third communication, in which even more beautiful and astonishing results are described.* A rabbit was treated in the same manner as the last, except that it was placed a short distance from an entire window, and not a hole in a shutter in this case the whole image of the window was accurately photographed-the panes white, the cross-bars red and sharply defined. It was found also, as might have been expected, that a better image was obtained from the eye of a rabbit just killed than from one actu

ally living, it being difficult in the latter. case to overcome the regenerating action of the choroid on the sight-purple.

Lastly, Kühne tried the simplest possible method of optography: the head of a rabbit was cut off, and, without any preparation, held for ten minutes under the middle of a large skylight. After the usual treatment with alum, the retina was examined, and on it was seen the perfectly sharp image of the skylight, with every pane and cross-bar accurately reproduced, and, at some distance, a smaller image of the second skylight of the room, the light from which of course fell obliquely into the eye.

To summarise-the essential conditions of vision are essentially photographic: the purple layer of rods and cones is altogether analogous to a sensitized plate, the color of which is discharged by light, but, during life, immediately renewed by the layer of epithelial cells in contact with it. And thus a great stride has been made in bringing the mysterious processes of life within the grasp of ordinary chemico-physical laws. Much yet remains to be done; the realm of things settled is still but an

isle of bliss Midmost the beating of a steely sea;

and it will be a long time yet before the desirable though perhaps somewhat dreary, state of things comes to pass, when the biologist may, according to his temperament, sit down and weep that he has no more worlds to conquer, or sing his Nunc dimittis at having no more problems to settle and no more battles to fight.-The Nineteenth Century.

Macmillan's Magazine.

TURKEY. By Lieutenant-Colonel James Baker, M.A. New York: Henry Holt & Co.

This is issued as a "companion volume" to Wallace's "Russia," and may fairly be conceded to take rank with it to the extent that as Mr. Wallace's book is the best and freshest treatise on the great northern empire, so Colonel Baker's is the best and freshest exposition of the condition, antecedents, and character of the Ottomans and their subject peoples; but in other essential respects the two works are in complete contrast with each other. Mr. Wallace is a trained scholar and industrious student; Col. Baker a travelled soldier who, though an acute observer, is not much given to severe intellectual analysis. Mr. Wallace devoted years to the patient accumulation, sifting, and comparison of facts bearing upon the various subjects of which he treats; Col. Baker is satisfied with such evidence as comes before him incidentally, as it were, and without any curious delving into obscure and apparently contradictory phenomena. Mr. Wallace is cautious in forming conclusions, and carefully qualified in their statement; Col. Baker unhesitatingly pronounces an excathedra judgment upon any thing that offers itself. Mr. Wallace is perfectly impartial and dispassionate in his search after the truth; Col. Baker starts out with a bias, which, though unquestionably honest, goes through the usual process of selecting and assimilating such facts as conform to it, and rejecting or belittling such as do not, thus becoming stronger at every step. Mr. Wallace's book would be valuable at any time, and is likely to be a standard work for many years to come; Col. Baker's derives much of its importance from its peculiar appositeness to the present condition of affairs in the East, and much of its interest from the presence of that personal element which constitutes the chief charm of a record of travel. Mr. Wallace will

long be the constant companion of all real students of Russian affairs; Col. Baker's animated narrative will be read with pleasure by a still wider circle, but the instruction to be gotten from it may be easily acquired by a single perusal.

Col. Baker left England for Turkey in the summer of 1874, and, after spending a few weeks at Constantinople, observing the changes that have taken place in the city of the Sultans since the epoch of the Crimean War, proceeded to Burgas, a port on the Black Sea just south of the eastern end of the Balkan Mountains. Here he bought horses and obtained a guide, and set out on a horseback journey of a thousand miles, which carried him nearly across Turkey in Europe from east to west, through the very heart of the Empire.

Crossing the Balkan range at its western extremity, he made an excursion into the rich valley of the Danube, and then proceded southwest to Salonica on the gulf of that name, near which he purchased an extensive farm, and linked his fortunes definitively with those of the country. During his long journey through the interior, and subsequently during his three years' residence on his farm in Macedonia, Col. Baker was brought in contact not only with the ruling caste of Turks, official and unofficial, but with nearly all the subject or Christian peoples. His book, though primarily a record of travel and personal observations, deals in detail and at considerable length with the origin, history, character, and qualities of each branch of the motley population of Turkey-in-Europe; and along with the narrative of personal experiences he gives the results of close study of the best available authorities, and of careful inquiry from natives, residents, and officials wherever he went. His compilations are interesting and apparently trustworthy, his personal testimony to any fact is unimpeachable, and the statistics he has gathered are copious, valuable, and fresh; and the only serious

blemish upon his work is that, as we have already intimated, he is dominated throughout by a strong preconceived bias. His bias is the characteristically English one that comes partly from a sincere belief in the good disposition of the Turks, but chiefly from jealousy and distrust of Russia. Col. Baker evidently believed that he had valuable facts to communicate, and he has communicated them in an interesting and attractive manner; but his book is, in substance, an apology for the abuses and atrocities of the Ottoman rule, and a bitter arraignment of Russian perfidy and intrigue, which he considers responsible for nearly all the recent" troubles."

In casting about for a remedy to the present deplorable condition of affairs, Col. Baker sees very clearly that education must be the great lever in the regeneration of the East; and it is agreeable to American readers to read his cordial and reiterated testimony to the excellent work which Americans are doing in this respect in Turkey. Robert College, founded by American liberality and conducted by American teachers, he pronounces the most useful educational institution in the Empire, and throughout the interior he found that the American missions were centres of a civilizing and enlightening influence among the people. He confesses that at one time he had an absurd prejudice against Americans, but that he was compelled not only to respect them but" to bow down in reverence before them" when he found what noble work they are doing in Turkey and Greece,

The volume is well provided with tables of population, taxation, military resources, etc., and, besides a good index, contains two colored maps-one in skeleton outline of the Turkish Empire in Europe and Asia, and another very full one of Turkey in Europe. ESSAYS ON POLITICAL ECONOMY. By Frederic Bastiat. English Translation Revised with Notes by David A. Wells. New York: G. P. Putnam's Sons.

Of all the numerous writers who of late years have undertaken the task of expounding Political Economy, it is conceded that none have equalled the late M. Frederic Bastiat in the skill, and force, and lucidity with which he laid bare to men of average intelligence the elementary principles of the science. His works have become classical in this department of literature, and readers who would find in Adam Smith, and Ricardo, and even Mill, only cumulative evidence of the dry and uninteresting nature of the "dismal science," will turn to these brief, simple, and homely expositions with never-failing pleas

ure and satisfaction. The "Essays" have long since been translated into nearly every European language, and are not unknown in this country; but the current English version was so imperfect that Mr. Wells was induced to undertake such a revision as would display their merits to the best advantage to a new world of readers. In carrying out this idea he has not confined himself to a mere rectification of the text, but has made such changes in the phraseology and illustrations as would make the exposition conform to the changed condition of affairs since 1848 (when it was written) and to the different circumstances of men, laws, and things at present existing in this country. English names have been substituted for French ones, dollars and cents put in place of francs and sous, and a few pertinent notes, drawn mainly from the recent economical experience of the United States, have also been added.

The Essays" in their present shape are probably precisely what M. Bastiat himself would have addressed to an American audience of this time if he had been writing for us instead of for a French audience of the period of 1848; and we take pleasure in indorsing Mr. Wells's commendation of the book to "all friends of economic studies and reforms in the United States," and in asking their cooperation in extending its circulation among the people.

PERU: Incidents of Travel and Exploration in the Land of the Incas. By E. George Squier, M.A., F.S.A. New York: Harper & Bros.

Students of American antiquities have already been placed under obligations to Mr. Squier by his researches among the ancient monuments of the Mississippi Valley and in various portions of Central America; and the sense of this obligation will be deepened by the present elaborate and instructive work. Of all the aboriginal civilizations that of the Incas is at once the most important and the most interesting, and has left behind it the grandest and most numerous monuments. Over nearly every portion of modern Perualong the coast, in the teeming valleys of the interior, and on the lofty mountain-sides—are scattered relics of the "Children of the Sun," including every variety of structure, from the vast ruins of Tiahuanuco, Cuzco, and Grand Chimu, and the stupendous aqueducts and highways, to solitary huacas and nameless graves in the nitrous sands of the desert. These relics have attracted the passing attention of many travellers, and a few native scholars have investigated various limited