are very short as well as very scarce, but they will soon be seen to multiply and grow rapidly, their complete evolution only requiring a few hours for its accomplishment. A rabbit, the blood of which merely exhibited a few bacteriums, from four to six thousandths of a millimeter in length, died at the end of four hours, and its blood, which was examined immediately afterwards, contained a considerable number of bacteriums, some of which, larger than any I had previously seen, reached the five-hundredth of a millimeter in length.

"In some animals the bacteriums are generally found larger than in others, but not presenting any other difference. In such cases their number was usually less. The length which the filaments sometimes acquired suggests their classification among the Confervæ ; but I omit, for the moment, the discussion of this question, as it has little importance in the present inquiry.

"The number of the bacteriums varies much between one animal and another. After my first inoculations this number decreased very rapidly, and they became eight or ten times less than the blood corpuscles. This led me to believe that their propagating power dwindled in rabbits, but I was afterwards convinced that such was not the case, as in a series of eleven individuals, one inoculating the other in succession, the blood of the tenth contained myriads of bacteriums like that of the first. I can only explain these variations by the changes in atmospheric temperature which occurred during my experiments.

"When the infected animal dies the bacteriums cease to multiply or grow, and in blood removed from its vessels they become destroyed or transformed. The loss of their primitive aspect is accompanied by loss of the power of propagating themselves in a living animal. Two inoculations effected, one with sheep's blood kept for eight days, the other with rabbit's blood kept six days, neither occasioned the spleen disease nor the formation of bacteriums.

"When fresh blood is rapidly dried in free air, the bacteriums preserve the faculty of inoculation, as I found in many experiments. The dried blood can sustain a temperature of 95 to 100° (C.) without this faculty being destroyed.

"Some fresh blood was enclosed in a tube and kept for ten minutes in water in ebullition. This blood being afterwards introduced under the skin of a rabbit, led to its decease, with formation of bacteriums in thirty-one hours. Cooking is therefore insufficient to destroy their vitality.

"In fourteen rabbits the mean duration of life after inoculation was forty hours; the shortest period being twenty-eight hours, and the longest sixty-seven. The duration was longer

in adults and old animals than in young ones. During this period the bacteriums are slow to appear, but from the moment of their occurrence the animal has but a short time to live. The longest interval that I have observed between the appearance of the bacteriums and the death of the inoculated animals was five hours, thus the mean length of the incubation period is thirty-five hours.

"During the incubation period the animal loses nothing in power or agility; it is only in the last two hours, when the bacteriums exist in notable quantity, that the rabbit ceases to eat or to run. It then lies on its belly, grows rapidly weak, and dies without any special symptom. Sometimes, however, death is preceded by slight convulsive movements."

M. Davaine goes on to say that autopsy shows a healthy condition of the large organs, but the heart and large vessels are distended by very cohesive clots. Coagulation of the blood is thus the only apparent cause of death. During life the microscope shows this coagulative action, as the increase of the bacterium is found to be associated with a viscosity of the red globules, and a tendency for them to adhere together. The large organs only contain the bacteriums as a consequence of their vascularity, and the spleen, which is very vascular, appears the focus of their reproduction.

M. Davaine concludes this paper by observing that experience shows the appearance of bacteriums in the blood precedes the phenomena of disease, and it is therefore natural to refer the latter to the former, which enjoy an individual vitality, and propagate themselves after the manner of living beings. While the blood only contains them in the germ; while their development is not effectuated, the morbid phenomena are not produced. But if the question is examined from another point of view, it seems probable that blood in which they have not made their appearance would be incapable of propagating them in a new animal, that is to say, that during the period of incubation they could not be sown, and the spleen disease (sang de rate) could not be communicated by inoculation.

In a third paper M. Davaine states that he inoculated a healthy and vigorous rabbit with three or four drops of blood from another rabbit infested with bacteriums, but still living. Forty-six hours after the inoculation, being six hours beyond the mean time of death, he examined the inoculated rabbit without finding any bacteriums. He then took from its ear twelve to fifteen drops of blood, that were injected into the subcutaneous tissue of a third rabbit, about two-and-a-half months old. Nine hours after this the rabbit first inoculated was found to contain a quantity of bacteriums, and some blood from its ear was introduced into the sub-cutaneous tissue of a fourth

rabbit. One hour after this last inoculation the rabbit first operated on died, and twenty hours afterwards the rabbit last inoculated died; but the rabbit that was inoculated with the blood in which the bacteriums had not made their appearance remained quite well. M. Davaine considers that no one can doubt the connection between the bacteriums and the disease, and he says "by their presence and by their rapid multiplication in the blood, they give rise, after the manner of ferments, to modifications in the blood, which speedily cause the decease of the infected animal."

M. Pasteur has shown that different kinds of fermentation and putrefaction are acts correlative with the lives of organisms of analogous character, and it seems probable that the laws of dialysis, investigated by Mr. Graham, are intimately connected with the chemical influence exerted by these creatures upon the fluids in which they grow.

M. PISSIS ON THE ANDES.

M. PISSIS, who has long resided in South America, has presented several memoirs to the French Academy on the geology of that country. These papers, having been considered by a commission composed of M.M. Elie de Beaumont, Boussingault, Danbrée, and St. Claire Deville, form the subject of a report which will be found in Comptes Rendus for 6th July, 1863, from which the following particulars are taken :

M. Pissis occupied part of his time in determination of mountain heights, among others those of the elevated peaks surrounding lake Titicaca. The report states, "the altitudes ascribed by him to Illimani and to Nevado de Sorata agree with those deduced from the measurements of Mr. Pentland, made during his second voyage to Bolivia, and with which M. Pissis could not have been acquainted. This fortunate agreement between two able observers leaves no doubt that Chimborazo exceeds by some hundred meters the two colossal mountains of Upper Peru.

"It was also reserved for M. Pissis to determine by a complete geodesic operation the height of Aconcagua, the most elevated of the yet known peaks of South America. Measured by means of two different bases, Aconcagua appears to have an altitude of 6834 meters, and thus to exceed Chimborazo by about 300 meters." In a note the commission refer to Mr. Pentland's estimation of 7300 meters for this mountain, which they say differs little from that of Captains Beechey and Fitzroy. They proceed to quote the words of M. Pissis, who observes

that, "in a geological point of view, this mountain, ordinarily spoken of as the volcano of Aconcagua, is in reality not volcanic. It is composed," according to M. Pissis, "from its base to its summit of stratified rocks, the lowest of which is composed of those same porphyries met with at every step on the Andes; while those on the summit, as judged of from some detached blocks, appear to belong to the cretacean system. It occupies the middle of a great circle situated a little to the east of the line of the Andes, from which it is separated by the valley in which the Rio de Mendoza has its birth. Some syenitic rocks show themselves in the lower part of this circle, which, at the time of my visit, was almost entirely filled with snow, which prevented my satisfying myself whether it contained eruptive rocks of more recent origin.'

The commission remark that, "in spite of the just reserve of M. Pissis, it is difficult to avoid the conclusion that the peak of Aconcagua occupies the bottom of a vast crater of elevation," a conclusion with which few English geologists would concur. Aconcagua is far from being isolated, as M. Pissis mentions three other peaks in its neighbourhood, reaching elevations of 6799, 6527, and 6347 meters. "Everything indicates that on that spot the most elevated mountain masses of the American Continent are found."

A study of the movements by which its present relief was imparted to the South American Continent has led M. Pissis to assert that its stratifications present nine general divisions:

"1. THE CHILIAN SYSTEM, i.e., the most modern of all, and posterior to the marine sands Atacama (remarkable for their deposits of nitrates) and to the formations of transport (terrains de transport) of la Paz.

"2. THE SYSTEM OF THE PRINCIPAL CHAIN OF THE ANDES OF CHILI, posterior to the lacustrine and marine deposits of Bolivia, of Chili, and of Patagonia, having a direction exactly N. and S., with appearance of trachytes and argentiferous seams.

"3. THE SYSTEM OF THE TRANSVERSE CHAINS OF CHILI, posterior to the calcareous and saline marls, having a direction approximately E. and W.: Labrador rocks and cupriferous beds.

"4. THE WESTERN CHAIN OF CHILI SYSTEM, anterior to the saliferous marls, posterior to the 'grès rouges' direction sensibly the same as in the first system: syenitic rocks, auriferous pyrites.

"5. THE EASTERN CHAIN OF CHILI SYSTEM, the elevation of which, contemporaneous with the eruption of quartziferous porphyries, occurred during the Jurassic period.

6. THE SYSTEM OF ITACOLUMI, the appearance of which

was posterior to the carboniferous lime, and anterior to the grès rouges of South America.

"7, 8, 9. ELEVATIONS OF SCHIST ROCKS OF SOUTH AMERICA, of which M. Pissis distinguishes three kinds, all very old."

M. Pissis considers that each movement of elevation was characterized by the emission of a particular rock, which takes the place of a characteristic fossil in the determination of its

age.

THE PLANET MARS: A FRAGMENT.

BY THE REV. T. W. WEBB, M.A., F.R.A.S.
(With a Coloured Plate.)

"I give the first watch of the night

To the red planet Mars."-LONGFELLOW.

FROM the tenor of some remarks which appeared in the present publication previous to the late opposition of MARS,* the idea may possibly have been entertained that the author of them intended to avail himself of that opportunity to make some detailed observations upon the aspect of this interesting planet. The impression would have been well-founded. I had purposed to undertake a careful examination of the physical features of Mars, as far as they would be brought out by the power of an excellent 5 inch object-glass, and securing, if possible, a delineation of as much of his surface as would at that time be exposed to view. It was indeed to be expected that the same task would be taken in hand by far superior observers, armed with much more powerful instruments, and, in part, favoured by purer skies; yet it did not seem to follow that a more humble attempt would be superseded, or would necessarily prove entirely useless; for it has not unfrequently been the case that inferior observations have found a place for themselves in that general accumulation of materials from which our final deductions have to be inferred. The peculiarly valuable investigations of Beer and Mädler were long carried on with an object-glass of not more than 4 inches aperture; and a quotation which they have employed will furnish an appropriate motto for any similar case:

"Quod potui feci; faciant meliora potentes."

The execution of my design proved indeed far more defective than I had anticipated. Absence from home, cloudy weather, and seasons of bad definition conspired to interpose

* INTELLECTUAL OBSERVER, viii. 132. See also xi. 376.