purifiers of the race, have been thus converted into terrible scourges and the agents of disease. Europeans are decimated by the locally innocuous parasites of Africa; the South Sea islanders are exterminated by the comparatively harmless measles of Europe.

A striking example of the disasters brought about by man's blind dealings with Nature-disasters which can and will hereafter be avoided by the aid of science-is to be found in the history of the insect phylloxera and the vine. In America the vine had become adjusted to the phylloxera larvæ, so that when they nibbled its roots the American vine threw out new root-shoots and was none the worse for the little visitor. Man in his blundering way introduced the American vine, and with it the phylloxera, to Europe; and in three years half the vines in France and Italy were destroyed by the phylloxera, because the European vines had not been bred in association with this little pest, and had not acquired the simple adjusting faculty of throwing out new shoots.

But it is not only by his reckless mixing up of incompatibles from all parts of the globe that the unscientific man has risked the conversion of paradise into a desert. In his greedy efforts to produce large quantities of animals and plants convenient for his purposes, and in his eagerness to mass and organise his own race for defence and conquest, man has accumulated unnatural swarms of one species in field and ranch and unnatural crowds of his own kind in towns and fortresses. Such undiluted masses of one organism serve as a ready field for the propagation of previously rare and unimportant parasites from individual to individual. Human epidemic diseases, as well as those of cattle and crops, are largely due to this unguarded action of the unscientific man.

A good instance of this is seen in the history of the coffee plantations of Ceylon, where a previously rare and obscure parasitic fungus, leading an uneventful life in the tropical forests of that country, suddenly found itself provided with an unlimited field of growth and exuberance in the coffee plantations. The coffee plantations were destroyed by this parasite, which has now returned to its pristine obscurity. Disharmonious, blundering man was responsible for its brief triumph and celebrity. Dame Nature had not allowed the coffee fungus more than a very moderate

Man comes in and takes the reins; disaster follows; and there is no possibility of return to the old régime. Man must make his blunders and retrieve them by further interference-by the full use of his intelligence, by the continually increasing ingenuity of his control of the physical world, which he has ventured to wrest from the old rule of natural selection and adaptation.

The adjustment of all living things to their proper environment is one of great delicacy and often of surprising limitation. In no living things is this more remarkable than in parasites. The relation of a parasite to the 'host' or 'hosts' in which it can flourish (often the host is only one special species or even variety of plant or animal) is illustrated by the more familiar restriction of certain plants to a particular soil. Thus the Cornish heath only grows on soil overlying the chemically peculiar serpentine rocks of Cornwall. The two common parasitic tape-worms of man pass their early life the one in the pig and the other in bovine animals. But that which requires the pig as its first host (Tania solium) cannot use a bovine animal as a substitute; nor can the other (Tania mediocanellata) exist in a pig. Yet the difference of porcine and bovine flesh and juices is not a very patent one; it is one of small variations in highly complex organic chemical substances. A big earth-wormlike stomach-worm flourishes in man, and another kind similar to it in the horse. But that frequenting man cannot exist in the horse, nor that of the horse in man. Simpler parasites, such as are the moulds, bacteria, and again the blood-parasites, trypanosoma, etc., exhibit absolute restrictions as to the hosts in which they can or can not flourish without showing specific changes in their vital processes. Being far simpler in structure than the parasitic worms, they have less mechanism' at their disposal for bringing about adjustment to varied conditions of life. The microscopic parasites do not submit to alterations in the chemical character of their surroundings without themselves reacting and showing changed chemical activities. A change of soil (that is to say of host) may destroy them; but, on the other hand, it may lead to increased vigour and the most unexpected reaction on their part in the production of virulent chemical poisons.

We are justified in believing that until man introduced his artificially selected and transported breeds of cattle and horses into Africa there was no nagana disease. The Trypanosoma Brucei lived in the blood of the big game in perfect harmony with its host. So, too, it is probable that the sleeping-sickness parasite flourished innocently in a state of adjustment due to tolerance on the part of the aboriginal men and animals of West Africa. It was not until the Arab slave-raiders, European explorers, and india-rubber thieves stirred up the quiet populations of Central Africa, and mixed by their violence the susceptible with the tolerant races, that the sleeping-sickness parasite became a deadly scourge-a 'disharmony,' to use the suggestive term introduced by my friend Elias Metschnikow.

4

The adjustment of primæval populations to their conditions has also been broken down by 'disharmonies' of another kind, due to man's restless invention, as explained a few years ago in the interesting book of Mr Archdall Reid on the 'Present Evolution of Man.' Not only does the human race within given areas become adjusted to a variety of local parasites, but it acquires a tolerance of dangerous drugs, such as alcohol and opium, extracted by man's ingenuity from materials upon which he operates. A race thus provided and thus immune imposes, by its restless migrations, on unaccustomed races the deadly poisons to the consumption of which it is itself habituated. The unaccustomed races are deteriorated or even exterminated by the poisons thus introduced.

Infectious disease, it was long ago pointed out, must be studied from three main points of view: (1) the lifehistory and nature of the disease-germ or infective matter; (2) the infected subject, his repellent or tolerant possibilities, and his predisposition or receptivity; (3) the intermediary or carrying agents. Whilst it is true that little or nothing has been done by the State in acquiring or making use of knowledge as to the first and second of these factors, with a view to controlling the spread of disease, it is the fact that much has been done both in the way of investigation and administration in relation to the third factor. The great public-health enquiries and consequent legislation in this country, in which scientific men of the highest qualifications, such as Simon, Farr, Chadwick, and Parkes, took part during the Victorian

period, have had excellent results; to them are due the vast expenditure at the present day on pure water, sewage disposal, and sanitary inspection. But little or nothing has been done in regard to the first and second divisions of the subject, in which the less organised portions of the British Empire are more deeply concerned than in waterworks and sewer-pipes. It is still contested whether leprosy (which is a serious scourge in the British Empire, though expelled from our own islands) is a matter of predisposition caused by diet or solely due to contagion; and yet it is left to individual practitioners to work out the problem. The State prepares vaccine lymph in a cheap and unsatisfactory way for the use of its, till recently, compulsorily vaccinated citizens; but the State, though thus interfering in the matter of vaccine, has spent no money to study effectively and to improve the system of vaccination. Here and there some temporary and ineffective enquiry has been subsidised by a government office; but there is no great army of investigators working in the best possible laboratories, led by the ablest minds of the day, with the constant object of improving and developing in new directions the system of inoculation. Surely if compulsion, or every pressure short of compulsion, is justified in enforcing vaccine inoculation on every British family, it would be only reasonable and consistent to expend a million or so a year in the perfection and intelligent control of this remedy by the most skilled investigators. Yet not a halfpenny is spent by the British Government in this way. Medicine is organised in this country by its practitioners as a fee-paid profession; but as a necessary and invaluable branch of the public service it is neglected, misunderstood, and rendered to a large extent futile by inadequate funds and consequent lack of capable leaders. The defiant desperate battle which civilised man wages with Nature must go on; but man's suffering and loss in the struggle-the delay in his ultimate triumphdepend solely on how much or how little the great civilised communities of the world seek for increased knowledge of nature as the basis of their practical administration and government.

E. RAY LANKESTER.

Art. VII. THE LAWS OF THE ANGLO-SAXONS.

1. Die Gesetze der Angelsachsen. Herausgegeben im Auftrage der Savigny-Stiftung von F. Liebermann. Erster Band: Text und Übersetzung. Halle: Niemeyer,

1903.

2. Quadripartitus: ein englisches Rechtsbuch von 1114 (1892). Consiliatio Cnuti: eine Uebertragung angelsächsischer Gesetze aus dem zwölften Jahrhundert (1893). Ueber Pseudo-Cnuts Constitutiones de Foresta (1894). Ueber die Leges Anglorum Sæculo xiii ineunte Londoniis collectæ (1894). Ueber die Leges Edwardi Confessoris (1896). Ueber das englische Rechtsbuch Leges Henrici (1901) and other treatises. By F. Liebermann. Halle: Niemeyer.

THOUGH Dr Liebermann has still something in store for us in the way of notes, index, glossary, and the like, the time has already come when we may rejoice in the possession of a really good edition of the oldest English laws, an edition which will bear comparison with the very best work that has hitherto been done upon any historical materials of a similar kind. That this task should have been performed by a German scholar at the instance of a German academy, and with the support of a German trust fund, may not be what we in England should have liked best, but must not detract from the warmth of our welcome and our praise. If Englishmen cannot or will not do these things, they can at least rejoice that others can and will.

The German occupation of a considerable tract of English history has been a gradual process. The sphere of influence becomes a protectorate, and the protectorate becomes sovereignty. The shore is surveyed and settled; and now with colour of right far-reaching claims can be made over an auriferous hinterland. How and why all this happened it would be long to tell, but a small part of the story should be remembered.

Few words will be sufficient to recall to our minds the nature and extent of the territory which, so we fear, is slipping from our grasp. Any one who, at the present day, desired to study, even in outline, the first six centuries of English history-those centuries which intervene