in the enlarged or swelled lymphatic glands, than in any other part of the animal's body.

8. In one and the same affected herd the older or more fully matured animals often recover, while nearly every young animal and particularly nearly every young pig under three months old, if once infested, will succumb to the disease, and is almost sure to die. This also may be considered as proof that the Schizophytes, or rather their zoöglæa-masses cause the disease by obstructing the capillaries. In older, and otherwise robust hogs the heart and the walls of the blood vessels are much stronger than in young pigs, and so it often happens that in the former the force of the blood current is strong enough to break and to disperse the zoöglæa-masses, and thus to free the ob structed passages, while in young, and especially in very young animals the pressure or the force of the blood current is insufficient, and then the passage is not freed, and exudation takes place, or the walls of the blood vessels are too weak, and then the latter yield and break and blood is extravasated. Usually both processes occur. Hence, while blood-extravasations in the lungs, are, as a rule, more frequent in young animals, other morbid changes brought about by Schizophytes, which have passed the capillary system in the lungs, and are forming their zooglœamasses in other parts or organs of the body, are on the whole more frequently met with in older hogs. Still, the latter, notwithstanding, have a much better chance of recovery than the former.

9. An animal which is recovering from an attack of swineplague, or in which the morbid process has ceased to be active, will yet for sometime discharge swine-plague Schizophytes with its excretions, and is able to communicate the disease to other healthy animals by polluting their food or water for drinking, consequently the organism of such an animal is not destitute of the infectious principle, but contains an abundance of the same in a potent condition, while its own tissues have become sterile, or are not any more acted upon, because some of the conditions required by the Schizophytes to form zoöglæa-masses and to propagate have become exhausted. In the lungs of an animal which was butchered two months after recovery, I found an abundance of swine-plague Schizophytes, but no zoögloa-masses. These facts, too, will be difficult of explanation, if a chemical poison or

virus, and not the Schizophytes constitute the infectious principle and the cause of the disease.

10. Swine-plague has a well-marked period of incubation, or as it has more appropriately been called stage of colonization, lasting from two to fifteen days, during which no morbid symptoms, with the exception, perhaps, of a somewhat higher temperature, can be observed. The average time which elapses after an inoculation or infection has taken place till plain symptoms of disease make their appearance, or till the morbid process has sufficiently advanced to produce external symptoms, or a visible disturbance of health, may be set down as from five to six days. All this is easily explained if Schizophytes constitute the cause, because those introduced from without are insufficient in numbers to cause at once important morbid changes; they must have time to undergo the necessary metamorphoses and to multiply within the animal organism, and this time varies according to the number of Schizophytes originally transferred to the condition or stage of development in which they are transferred, and to the degree of so-called predisposition or favorableness of conditions existing in the infected animal. As a rule, the larger the amount of the infectious material introduced and the richer the same in swineplague Schizophytes, the shorter the period of incubation, or stage of colonization.

On the other hand, if the infectious principle were a chemical poison or virus, its action, one should suppose, would, under all circumstances be exactly the same, and the malignancy of the morbid process and the time required for its development would not be influenced by, or be dependent upon so many conditions, such as the individuality, age and temperature of the animal, the time and season of the year, the number and stage of metamorphosis of the Schizophytes contained in the infectious material and other yet unknown conditions. A poison. or virus, indestructible by water and air, and not affected by dilution, no matter how far it may be carried, one should suppose, would act with great uniformity. Consequently one is obliged to conclude that the Schizophytes, and not a chemical virus, must, and do, constitute the cause.

II. The infectious principle undoubtedly consists in something that is destroyed and made ineffective by putrefaction, because infectious material, such as blood, blood serum, lung exudation,

other morbid products, etc., if putrefied, can be consumed by healthy animals without communicating the disease, and if used for inoculation, such putrefied material may cause septicemia, but never produces a genuine case of swine-plague. Further, as has been previously mentioned, swine-plague Schizophytes cannot any more be found in the blood, blood serum, morbid tissues and morbid products, etc., of hogs which are diseased with, or have died of, swine-plague after putrefaction has set in, or in other words, after putrefaction bacteria, and particularly Bacterium termo, have made their appearance in large numbers. So, for instance, blood which has become sufficiently putrefied to assume a purplish color, is destitute of swine-plague Schizophytes. If these two facts are connected, it becomes evident that infectious substances or media lose their efficacy, or their power to communicate the disease to healthy animals simultaneously with the disappearance of the swine-plague Schizophytes, and vice versa, the latter disappear at the exact time at which the infectious substances or media cease to be infectious. Does this indicate a close relationship between the swine-plague Schizophytes and the infectious principle, or can such a remarkable coincidence be rejected as merely accidental? Further, is it more rational to accept as the cause and infectious principle of swine-plague, an unseen virus or something which nobody has ever produced, nor ever will produce, but which, notwithstanding, is indestructible by water, air and dilution, and possesses the remarkable property of making its exit at the very moment at which the swine-plague Schizophytes are destroyed, or caused to disappear by putrefaction, than to regard the latter, the Schizophytes, which do exist, are present, can be seen, have been shown and, moreover, possess all the properties and peculiarities manifested by the infectious principle, as the true cause of the morbid process and the propagators of the disease? I, for one should not think so.

12. It is an established fact that the morbid process, which invariably affects the lungs, will also develop in all such other parts. or organs as may happen to be wounded, inflamed, or in a state of congestion-for particulars I have to refer to my reports-and thus some other parts besides the lungs may sometimes become just as much, or even more affected than the latter. So, for instance, if a pig has been ringed, or been castrated, and a perfect healing has not yet taken place when the animal becomes infected,

the parts yet more or less inflamed invariably become a prominent seat of the morbid process. All this is explained if the Schizophytes constitute the cause, as all recently wounded parts are comparatively rich in blood, and their capillaries, on account of the yet existing congestion or inflammation, are easily obstructed; but I should find it very difficult to give an explanation, if a poison or chemical virus constitutes the infectious principle and the cause of swine-plague. A chemical poison or virus, one should suppose, would possess special affinity to certain parts or tissues, and therefore cause the morbid process either to develop invariably in one and the same part of the body, or to attack in all cases the whole animal organism.

13. Antiseptics, or medicines, which are either directly poisonous to the lowest forms of organic life, or destructive to some of those conditions necessary to the metamorphoses and propagation of the simplest forms of organic life, such as Schizophytes, and among those antiseptics particularly carbolic acid, iodine, hyposulphite of soda, benzoate of soda, thymol, etc., have proved to be almost sure prophylactics. Their use, combined with strict separation, will prevent the outbreak of swine-plague in animals which have been inoculated or have undoubtedly become infected. As one of the conditions necessary to the development of swineplague, it seems, must be considered a certain degree of animal heat. At any rate, after or while the animal heat of a pig is reduced by a continued treatment with carbolic acid from the normal 102 or 103° F., to an abnormally low temperature of a few degrees below 100-in several cases it was reduced to 96° and 97°-nearly every inoculation with fresh infectious material has proved to remain ineffective, and the few which did not remain ineffective were followed by an unprecedentedly long period of incubation and a very mild form of the disease. Comment will not be necessary. The various antiseptics which have proved to be good prophylactics, are very dissimilar in their chemical action and affinities, and therefore their prophylactic effect cannot very well be explained if the infectious principle consists in a chemical poison or virus, but admits explanation if something endowed with life and power of propagation constitutes the cause of swine-plague.

MEXICAN CAVES WITH HUMAN REMAINS.

BY EDWARD PALMER.

EAR the western border of the State of Coahuila, Mexico, are

NEAR

to be found several caves in the limestone formation of the mountains. In these caves human remains were found. This section of country under consideration is commonly called the Lajona, which means overflowed. During the rainy season, which is the months of July, August and September, the river Nazas overflows its banks, and inundates the valley. Of late years cotton and corn has been cultivated. To prevent the excess of water from destroying the plants, large canals are dug round the fields, and connected with the river. These canals are used for irrigating the crops. Previous to the advent of the Spaniards this section could not have been much cultivated, as the good land was overflowed at the growing season, and previous to the rains it was too dry for crops to mature before the wet season, when the overflow would destroy them.

It presents to the eye of an observer a country unfit to sustain a large permanent people without modern appliances. Its numerous mountains are dry and rocky, without trees, though having a few stunty bushes and plants in the shady recesses. The valley also is as dry and barren except immediately about the receding waters. The plants naturally produced in a country of this character are the cactus, agave, yucca, mesquite, Larrea mexicana, and allied forms. These are either armed with thorns, or are so excessively bitter that neither wild nor domestic animals. using them for food can exterminate them.

Animals are scarce; deer, two species of rabbits, skunk, badgers, ground squirrels, and rats, with snakes, lizards, birds and fish, are limited in number, except rabbits and blackbirds.

The food products of a country determines its capacity to sustain life, especially when without domestic animals, and situated as these people were in the midst of a desert waste without any productive country immediately near from which to draw food supplies from, moving from place to place as the food and water supply admitted during the dry season, in the wet they could with pack-animals move their effects to the near mountains in which water is then to be found. During the dry season there are but two plants in that section, which could be counted upon for a supply of food, game being merely incidental.