duration, or whether it will take a place in the treatment of locomotor ataxia, depends on how much is expected of it. Considered as a curative agent, it surely will disappoint. Considered as a palliative agent, the patient himself, reflecting upon his condition in former days and that of to-day, will pronounce it the only remedy that gives so much relief in so short a time.

Charcot has also applied suspension in other diseases of the nervous system. In two cases of Friedreich's disease, gratifying results have been obtained. In spastic paraplegias the first application seemed rather to aggravate the symptoms. Subsequent suspensions have, however, proven beneficial. In Parkinson's disease (paralysis agitans) the patients have experienced much relief. Two cases were under observation, and both are well satisfied with the results of the suspension. The rigidity and stiffness have given way to a great degree. The sensations of chaleur (flushings) have abated, the sleep is improved, and the gait has become less fatiguing.

The tremor, however, has shown no sign of disappearing, but remains as persistent as ever.

Microscopy.

Micro-Organisms, and their Relation to Disease.

BY SAMUEL N. NELSON, A. M., M. D., OF BOSTON, MASS., SURGEON TO THE Soldiers' home iN MASSACHUSetts.

Read before the American Academy of Medicine, and Approved by the Council for Publication.

THE rôle of the microorganisms called bacteria is at present probably occupying the attention of more scientific men than any other subject in modern science. Great numbers of observers are at work on both continents in the solution of the germ theory of disease. Comparatively unknown till within a few years, on account of their very minute size, these microorganisms attracted attention and experimentation chiefly when the improvement of the microscope allowed objects of their size to come within the limits of its powers of observation. At first simply recognized as existing, their persistence and universality demanded question as to what they are, their origin, and object.

The history of these microorganisms is related to that of spontaneous generation, to that of the fermentations, to the pathogeny and therapeutics of a great number of virulent and contagious affections; and in a more general manner to all the unknown which, notwithstanding the efforts of modern science, still surrounds the origin of life and its preservation.

The bacteria are the lowest of organisms, belonging to the vegetable kingdom, and are thus defined by the botanists, who have most recently occupied themselves with them; "Cells deprived of chlorophyll, of globular, oblong or cylindrical form, sometimes sinuous or twisted, reproducing themselves partly by spores and by transverse division, living in isolated or in cellular families, and having affinities which approach them to the algæ, and especially to the oscillariæ.'

The atmosphere transports myriads of microscopic plants and animals. M. Miquel has pursued interesting studies upon them. M. Pouchet has devised the aëroscope, that bears his name, for collecting dust from the air which contains remnants of articles that we use, existing in the condition of impalpable dust, also pollen of plants, particles of mineral matter, and the spores of cryptogams, the moulds and algæ. Some micrographers have suggested that germs may be transported by the vapor of water; but Miquel's experiments show that the evaporation from the ground never carries any schizomycetes with it. On the other hand, dry dust, especially from hospitals, etc., is charged with microorganisms. The greatest labors, however, have been employed concerning a different class of organisms than the algae and moulds. The plants comprising this group, under the common designation of bacteria, in consequence of their extreme minuteness and refractive power, are invisible in the preparations of the aëroscopes, and are recognized only by the higher powers of the microscope.

The first observer who recognized the microorganisms was Leeuwenhoeck, as early as 1675. While examining with his magnifying glasses a drop of putrid water, the father of microscopy remarked with profound astonishment that it contained a multitude of little globules which moved with agility. During the following year he observed the presence of bacteria in feces and in tartar from the teeth.

M. Cohn is a naturalist who has occupied himself very much with the bacteria. In 1853 he published his first re

searches upon this subject, and twenty years later there appeared a series of "Memoirs" devoted to these organisms. In the first paper he gives an exposition of his researches upon the organization, development and classification of the bacteria, and upon their action as ferments. His classification is:

1. The sphærobacteria, or globular bacteria.

2. The microbacteria, or rod bacteria.

3. The desmobacteria, or filamentous bacteria. 4. The spirobacteria, or spiral bacteria.

This classification has probably been accepted by more germ theorists of to-day than any other classification.*

The smaller spherical bacteria may be confounded with various objects; e. g., molecular granules, fat globules, amorphous precipitates, etc. To distinguish these pseudobacteria Nägeli says: "There are but three distinctive signs which enable us to recognize with some certainty that the granules under consideration are organisms: spontaneous movement, multiplication, and equality of dimensions, united with regularity of form." To which may be added the action of re-agents.

The atmosphere is laden with these microorganisms. Developing in the organic infusions into which they fall, they soon determine their complete decomposition; for during their growth bacteria live upon the nutritive material, as all other plants do upon their soil. This is putrefaction, and they are always present as the cause. As is well known, bacteria are always present in some form or other in fermenting liquids. Fermentation only occurs after the access of particles from the outer world, and it is asserted by the supporters of the germ theory that these particles are organisms or their spores, and that it is by the growth of these organisms in the fermenticible material that it undergoes alteration. The essentials for the production of new forms are a putrescible body, water and air; while heat, light and electricity favor the process.

As Sir William Roberts says: "Without saprophytes there could be no putrefaction; and without putrefaction the waste materials thrown off by the animal and vegetable kingdoms could not be consumed. Instead of being broken

The classification proposed by Koch is now quite universally accepted. The term bacteria is used in the general sense, including both the micrococci -the ball forms-and the baccilli-the rod forms.-Written since reading of the paper.

up, as they are now, and restored to the earth and air in a fit state to nourish new generations of plants, they would remain as an intolerable incubus on the organic world. Plants would languish for want of nutriment, and animals would be hampered by their own excreta, and by the dead bodies of their mates and predecessors-in short, the circle of life would be wanting an essential link. A large proportion of our food is prepared by the agency of saprophytes. We are indebted to certain bacteria for our butter, cheese and vinegar. Our daily bread is made of yeast, and to the yeast plant (discovered in 1836 by Cagniard de la Tour, and also independently by Schwann about the same time) we also owe our wine, beer and spirituous liquors. As the generator of alcohol, this tiny cell plays a larger part in the life of civilized man than any other tree or plant.'

Unfortunately for us, however, they have a powerful potency for evil also, and it is the noble aim of science to be able, by thorough study of the conditions under which that potency is acquired and exerted, to keep it under efficient control.

Much still remains to be determined with regard to the disease-producing possibilities of the germs that in invisible clouds drift in the atmosphere. The more delicate and exact methods of the most recent observers-Koch, Pasteur, Tyndall, Ehrlich, Ogsten, Sternberg and others-with regard to their nature seem to show that there are many varieties of them, each of which has its own conditions of growth, requiring or developing best in a particular soil. Different species multiplying in different media and varying in their susceptibility to different temperatures and to different chemical re-agents. Apparent identity of form does not necessarily indicate identity of nature. They are not convertible into each other. Each species produces only itself, and is produced by itself alone, and when introduced into a substance that affords a favorable soil for its growth, always produces the same results. These results are not produced suddenly, but are of gradual development, progressing with the slow and steady multiplication of the organism. They may be cultivated artificially in either solid or liquid media. The best known and most commonly used solid medium is nutrient gelatine, which unites the advantage of transparency with that of solidity; but it has the disadvantage of melting at a comparatively low temperWhen it is desired to cultivate bacteria at a temper

ature.

ature approaching that of the human body, sterilized blood serum may be used, or a preparation of agar-agar, a Japanese sea moss. The cut surface of a freshly sterilized boiled potato is also a very satisfactory culture medium under some conditions.

For liquid cultures a tube or bulb hermetically sealed, containing a sterilized infusion of hay or meat, is used, which will remain clear indefinitely. When, however the germs are introduced in ever so minute quantity, they begin to develop, after a varying interval of one to twenty days, and then they rapidly increase. The liquid infusion, previously clear and pellucid, becomes more or less cloudy or turbid. When in this condition, we may be sure of the presence of rapidly increasing microorganisms in great numbers, as the microscope will invariably reveal.

It has been a widely disputed question as to whether bacteria ever occur in the animal in a perfectly healthy state; the affirmative view having been taken by Billroth and some others; but it is denied by Koch, by Pasteur and by Ehrlich, who state that they have never detected bacteria in the healthy animal. The failure of putrefactive bacteria according to experiments, would go to show inability to struggle against the normal cells indigenous to the soil upon which they were planted. Some bacteria showed power of existence only in tissue in which vitality had entirely ceased, while others seemed to possess the power of existence in the presence of the animal cells when the latter suffered from impairment of nutrition, and the tide of life was turning against them. Abnormal composition of the blood seemed to favor the development of some bacteria, after they had found their way into the tissues.

The theory of a causal relation between bacteria and diseased processes has recently received a wide acceptation. In some diseases this relation is established, while in others it is presumed, on the ground that bacteria are found in the blood and diseased products. As additional evidence in favor of special bacteria for different diseases, the fact is advanced that bacteria found in different diseases have been discovered to have different morphological and chemical properties; to which may be added of still greater value, the different appearances presented by the colonies growing upon solid culture media.

Admitting this causal relation of bacteria to disease, it must be demonstrated by successive cultures of the bacteria