or by any implication for any debt, or liability in any form, which said company may incur, nor be held as guaranteeing any engagement or contract of said company, or as having assumed, by virtue of this act, any responsibility for the acts or proceedings of said company in any foreign country, or contracts or engagements entered into in the United States.'

Congress adhered to its former action, and did not grant any subsidy to the company. In deference, however, to the character of the enterprise, and to the interests of our sister Central American republics, a law was passed appropriating a sum of money and authorizing the appointment of a commission of three engineers, one from the army, one from the navy, and one from civil life, to make an inspection of the line and route of the proposed Nicaragua Canal as laid out by the company, and especially to make a detailed estimate of the cost of execution. This commission went personally to the site and line of the canal route. They made a skilful and careful examination of the line, a particular calculation by itemized sections of the cost of completion, returned home, finished their report, and filed it on the 7th day of February, 1896.

This report by the government board of engineers, compared with the report of the engineers of the company, became the subject of quite animated discussion and of special notice in the Senate in the winter of 1897.

To summarize this state of affairs, the total estimate of the Canal company for the construction and completion of the canal is $66,466,880. The estimate of the governnient board of engineers is $133,472,893, twice that of the company, and within $7,000,000 of the former estimate made by the commission appointed by Pres. Grant in 1874.

There is surely no valid reason why, if our government is to furnish the funds for the construction of the canal, it should not also directly control and administer the same, in conjunction with the Central American governments interested, under a treaty with them concluded for that purpose.

There is certainly no reason why the government of the United States, in relation to the building, completion, and future operation of this great canal, should treat with a private corporation whose only claim to consideration rests in the total discredit and disaster which have accompanied its attempt in the execution of the work.

And it is to be especially noted that although the government of Nicaragua publicly charges the Maritime Canal Company with violations of the concession, and with inexcusable breaches of contract, yet neither of the Central American republics has made any opposition to the enterprise itself, or to the construction of the canal by our government.

A condition quite fortunate is thus shown, because it is not possible that any power could build or operate this ship canal in the country of an unfriendly population. This work is not like that of Suez or Corinth. Those are canals built by excavation on the sea level, as before stated. To destroy them would require the slow process of the excavation of another channel to drain away their waters, or the filling up of the present one in use; but the Nicaragua canal, with its double system of dams and locks, would be peculiarly sensitive and liable to injury, by either public or private enemies, as there are many places along the line at which an hour's work with the pick and shovel, to say nothing of the use of explosives, would let the water rapidly escape, and so wreck the whole system.

Congress, in accordance with this recommendation, on the 4th day of June, 1897, authorized the appointment of a commission of engineers to make another survey and estimate of the cost of construction, and to further examine as to the proper route, and as to the feasibility of the Nicaragua canal.

This commission has since been appointed by Pres. McKinley, and is now engaged in the performance of its duty. Our government is awaiting its report.

Three things are necessary to the consummation of this enterprise: First, funds to be furnished by the government of the United States. Second, the perfect amity and friendly co-operation of Nicaragua and Costa Rica in the work. Third, a reasonable assurance of its feasibility, and of the amount of money needed to construct and complete it.

The three republics could under such auspices thus give to the world an American canal under American control.

"BACTERIOLOGY."

By GERMAN SIMS WOODHEAD, M. D.

(Abstract from Proceedings Institution of Civil Engineers [England]. Vol. CXXX, 1897) We have already mentioned that bacteria may be roughly divided into two classes-those which have the power of taking up oxygen from the air and those which, although they require oxygen, as a rule obtain it from carbo-hydrates or from substances that contain a considerable quantity of oxygen in their composition, but which, deprived of their oxygen, rapidly break down to form substances of a less complex nature. It must be remembered, however, in this connection that no hard and fast line can be drawn between aerobes and anaerobes, as they are called--that is, between those organisms that require air and those organisms that can do without it, as under certain conditions an aerobic organism can lead an anaerobic existenee, that is, can so far adapt. itself to circumstances that when it is removed from air it makes violent efforts to obtain its oxygen from substances that contain

oxygen in considerable quantities, taking them up best, of course, from those substances in which the oxygen is in a condition of loose combination; whilst, on the other hand, an anaerobic organism may grow fairly luxuriantly in the presence of air, although it is found that, under certain circumstances, it does not give rise to its characteristic products. Those organisms, which have the power of adapting themselves to their surroundings, are usually described as facultative aerobes and anaerobes, but although they can so far adapt themselves to the altered conditions, their life history and the results of their vital activity are considerably modified. Let us take as an example one that actually occurs in nature. If instead of water, as above, some surface soil is taken for the seed material for gelatine plates, the individual organisms contained in the soil are isolated; if, at the same time, a very minute fragment of this soil be put into gelatine containing a small quantity (2 per cent) of grape sugar, or a still smaller quantity (1⁄2 per cent) of formate of soda, two things will soon be noticeable. In the gelatine plate culture, especially if the layer of gelatine be of some little thickness, it will be observed that on the surface numerous colonies grow with very great rapidity, some of them producing color, others of them liquefying the gelatine, the whole of the organisms on the surface showing luxuriant growth. Just beneath the surface of the gelatine, and down in the substance, will be seen a number of small brown points, which are certainly colonies of organisms, but they progress so slowly and to such small size that it is evident that the conditions for their growth are not so favorable as are those on the surface, the only difference in this case being, apparently, that those on the surface have a plentiful supply of oxygen, whilst those in the depth do not receive this supply, although there is a small quantity, or they could not grow at all. Now, examining the formate of soda gelatine in the test tube, the organisms on the surface will still be seen to be growing, though not so luxuriantly, as a rule, as on the plate. Near the surface round colonies may also be seen, but down in the substance of the gelatine large colonies, sometimes liquefying the gelatine, sometimes producing gas in considerable quantity, are found. These are the anaerobic organisms which are breaking down the gelatine in the absence of air, just as those on the surface break down the gelatine in its presence. It will be found that in soil taken from very near the surface the number of anaerobic organisms, as compared with the aerobic organisms, is comparatively small. If, however, we take soil from a greater depth and treat it in the same way, the proportion of anaerobic to aerobic organisms is much larger, and going still deeper we come to a layer in which practically only anaerobic bacteria are found, whilst in deeper layers still there are no organisms of any kind.

In nature the process of decomposition of organic matter goes on most readily in these superficial layers of earth, and in the presence of the atmosphere, and the porous soil may be said to

take the place of spongy platinum, in which, as we know, oxidation takes place very readily. The upper surface of this porous soil, usually well supplied with air and moisture and organic matter, is a capital feeding-ground for micro-organisms, which, breaking up its materials, oxidize them into substances which are capable of being utilized by plants. Most of the organic matter brought to the surface of the soil is broken down by these aerobic organisms, air being carried down along with the rain or sewage, and then, as this organic matter is broken up, some of its constituents are used by the bacteria, and others are, during the breaking down of the molecule, left in a nascent condition ready for oxidation by the air that has been left by the organisms. The anaerobic organisms found in the deeper layers of the soil, as we have indicated, give rise to a second kind of decomposition. A certain proportion of the organic matter escapes the action of the aerobic organisms, but it has still to run the gauntlet of the anaerobes. It is assumed that, having been washed deeper into the soil and living, as it were, at some distance from the atmosphere, these anaerobic organisms (originally aerobic) have been unable to obtain free oxygen, and have thus been compelled to develop the power of wresting oxygen by force, as it were, from the oxygen-containing bodies that come down to them from the surface, usually using part only of the combined. oxygen, and setting free another part to be used up in the oxidation of portions of the organic matter that still remains. So completely do these organisms use up the food that has come from the surface that at a depth of about 12 feet no micro-organisms at all can, as a rule, be found. The relation of this to our water supply and to the treatment of sewage is obviously one of extreme importance. As I have stated elsewhere, if water can be taken from near the surface of the soil in which there is a large quantity of organic matter present, there must necessarily be numerous aerobic putrefactive organisms in it, whilst surface drainage-water will invariably contain those organisms usually found in sewage and in excrement. If, however, water be taken directly from the deeper layers of soil, putrefactive organisms are usually absent, but a number of what are called water-organisms, non-spore-bearing harmless bacteria, are found.

If the water be kept perfectly undisturbed, unoxygenated, and at a comparatively high temperature, these water-organisms increase in number at a very great rate. It has been found, as a result of numerous bacteriological examinations by various observers, that, if in a single cubic centimetre of any specimen of freshly-drawn water, 200 bacteria are found at the first examination, by the end of twenty-four hours the number may have risen to 5,000, and the end of a second twenty-four hours to 20,000, and twenty-four hours later the multiplication has become so rapid and has gone so far that they are no longer countable. After a short time this multiplication ceases until the water is reoxygenated. If, however, water be taken from a much deeper

layer, micro-organisms are found to be almost, or entirely, absent, and not only micro-organisms, but organic matter, which has not been washed down to such a depth as that from which this water has been obtained. There are cases, however, of deep wells and springs, in which, although micro-organisms are practically absent, organic matter is still present in appreciable quantities. It is evident, then, that the superficial layers of earth act not only as mechanical, but also as biological filters. The water, with its contained organic matter, passes through the surface layers, in which bacteria can grow, down to those layers in which there are no organisms, the organisms not passing down with the water, first because they are held back mechanically, the soil acting as a porous filter, by which even extremely minute solid particles are held back, but also because most of the bacteria being anaerobic cannot leave the surface with impunity, most of those that are carried down by the water dying off as their supply of oxygen is gradually removed; for, in consequence of the rapid oxidation that is going on at the surface, very little free oxygen is left for the use of bacteria even in comparatively superficial layers. The few organisms that can persist develop the anaerobic faculty and utilize the small quantity of oxidized material that has been converted into inorganic matter and used up by growing plants. This amount is small because the reduction of the small quantity that remains after the plants are satisfied is soon completed, and bacteria can no longer obtain any material for their nutrition. When these conditions are borne in mind, it becomes evident that such valuable information as to the character of any water and its suitability for domestic use may be derived from a bacteriological examination, it being understood that the mere number of organisms can convey little accurate information except in those cases where it is examined at once, and even in such cases the information obtained is not of prime importance. Quite recently you have had amost animated discussion on the action of biological filters. So important is this question, and such a prominent part is it destined to play in the future of sewage disposal, that the discussion extended, I believe, over three nights after the paper had been read, and much still remains to be said on this most important question. I should like at this stage to indicate that what takes place in the breaking down of organic matter in nature may also take place, under certain conditions, in artificially-prepared filters. The main factors in the process are essentially the same as those already described. In the process it is necessary (1) to get all solid matter into solution; (2) to supply as large a quantity of oxygen in as short a time as possible to this organic matter; (3) to attack the organic matter in solution by means of micro-organisms and to so break it up that the various elements of which this complex material is composed may be thrown into an unstable or nascent condition so that the oxygen present may have an opportunity of entering into combination and of forming what are called oxodized sub