BACTERIUM

( Bacterion , a little rod). Since the publication of the researches of Profe or Cohn, of Breslau, upon the nature of this organism, the idea previously entertained by Ehrenberg and others as to its animal origin has been long abandoned, and microscopists now very generally regard it as belonging to the vegetable kingdom. It is probably one of the lowest and most simple forms of vegetable or animal life, and consists of an envelope more or le enclosing protoplasm—the nitrogenous substance from which the cell nucleus is formed. Dr Lionel Beale very carefully crushed a very large bacterium while under observation by the microscope, and when the external membrane was ruptured the protoplasm was seen to escape, and to exhibit what Dr Beale regards as vital movement. In form, bacteria may be either globular, rod-shaped, egg-shaped, or filamentous. Cohn has described a variety presenting the appearance of beaded chains, or aggregations. Bacteria vary considerably in size, some being as much as 1 ⁄ 3000 th of an inch in length, whilst others are le than 1 ⁄ 10000 th, and are only visible by the aid of a gla of very high power, such as the 1 ⁄ 50 th of an inch objective. Dr Beale says, “The germs from which the little particles spring are far more minute and more difficult to identify. They appear as minute specks, the largest of them exhibiting a circular outline, and probably being spherical. The smallest are too minute to be discerned with the highest magnifying powers at our command. If a specimen of fluid in which these particles are rapidly growing and multiplying be carefully examined, many points will be observed to appear from time to time. After watching with great care for a considerable time a given spot I have a ured myself that new particles actually come into existence; and that one does not, after intently watching for a time and concentrating the attention upon a certain space, merely see one coming into view one after another, as star after star. The material in which the minute germs of bacteria are imbedded, and which, at least in part, consists of formed the capsule of fungi consists. It is, perhaps, almost as soft as mucus. I believe that even the most minute bacterium germ is surrounded by a layer of such soft formed matter, in which very minute particles of bioplasm (protoplasm) divide and subdivide before they attain even the 1 ⁄ 100000 th of an inch in diameter. When, therefore, bacteria in an early stage of development dry, it is not po ible to identify them. When moistened, the dry ma swells up, and the bioplasm in the soft mucus-like matter grows, each particle producing a fresh investment of formed material, and then if the conditions are favorable, the germs either at once divide and subdivide for a time, or grow into perfect bacteria, which move freely and grow and multiply in this more advanced stage of development.” Bacteria increase by bisection, and when the surrounding conditions are favorable their rate of production is marvellous. It has been computed that an individual bacterium will generate nearly 17,000,000 of its fellows within twenty-four hours. The very probable vegetable origin and nature of bacteria insisted upon by Profe or Cohn not only appears to derive great support from his researches into the metamorphoses they undergo during development, ., but also from their behaviour with certain chemical reagents. For instance, it was found that boiling them in solution of potash had no effect, and also when treated with sulphuric acid and iodine they deported themselves somewhat as cellulin does under like circumstances; although from their extreme minutene any changes that take place in their ti ue are very difficult to observe. Another remarkable analogy presented between bacteria and plants is the manner in which they both a imilate the elements of which they are built up; for they derive their nitrogen not from previously existing albuminous compounds, but from ammonia. They may be made to develop themselves in any fluid if the fluid contains an organic substance in which carbon is present, a nitrogenous substance which need not be organic, and a phosphate. They appear to derive their carbon by the decomposition of almost any substance, containing this element except carbonic acid, and they will obtain their nitrogen from a nitrate, the nitrate becoming reduced to the state of a nitrite. A knowledge of these facts will of course indicate the method to be followed if we wish to obtain bacteria. All that we have to do is to prepare a liquid that fulfils the conditions just stated. Dr J. Burdon Sanders on gives the following formula for one:—Phosphate of pota ium 1 ⁄ 2 per cent., sulphate of magnesium, 1 ⁄ 2 per cent., di olve in water having a trace of phosphate of calcium in suspension, and then add a per cent. of tartrate of ammonium, and boil the mixture. If properly boiled the liquid will be free from bacteria; but the contact of almost any organic substance, for example, a drop of water, a pinch of hay, a morsel of meal, ., will cause their appearance. The tenacity of life exhibited by the bacteria is extremely great. Dr Beale says, “Extreme dryne does not destroy them, and they withstand a temperature far below the freezing point; and that under adverse circumstances they remain dormant, and are not destroyed by a degree of heat which is fatal probably to every other living organism.” Bastian says that the germs of bacteria are destroyed at a temperature of 160° F., but others are of opinion that under certain circumstances these germs are not killed at 212°, and that they may increase and multiply after having been exposed to this degree of heat. Profe or Tyndall indeed has shown that in one experiment heating for a quarter of an hour at a temperature of 230° F. was insufficient to destroy them, whilst in another the five minutes’ exposure of an atmosphere containing them to the incandescence of the voltaic current failed to kill them. Cohn relates that manufacturers of pots of preserved peas at Lubek have since 1858 been obliged to cook them in a solution of 28 per cent. of salt, at a temperature of 226° F., to prevent the putrefaction of their contents, as in warm years nearly half the pots were found to be spoiled. In experiments made in conjunction with Dr Hare, Cohn found that in infusions boiled for le than fifteen minutes organisms were, without exceptions, developed. Somewhat lower temperature proved fatal to the great majority of bacteria. Those that survived were all found to belong to the genus Bacillus , and among bacilli to the species Bacillus subtil is . The experiments of Drs Ferrier and Burdon Sanders on would seem to show that bacteria do not nominally exist in the fluids and ti ues of the body, but that their presence in the animal fluids may be traced to external surface contamination with ordinary water, the extent of their development being in proportion to the amount of the contamination. They contend that different varieties of water po e different degrees of what they term the ‘zymotic power.’ They examined the waters supplied by the several London water companies, and they found them to consist of varying degrees of bacterian impurity. They a ert that all except freshly distilled water teems with invisible germs of bacteria. Writing of the universality of the presence of bacteria and bacterian germs, Dr Beale remarks:—“It would be difficult to say where bacterium germs do not exist. In air, in water, in the soil adhering to tiny particles of every kind, in every region of the earth, from the poles to the equator, they are found. In the substance of the ti ues—nay, in the cells of almost all plants, and in the interstices of the ti ues of many animals—bacteria germs exist. I know not what part of the body of man and the higher animals is entirely destitute of particles which under favorable circumstances develop into bacteria. Upon the skin and the surface of the mucous membranes they exist in profusion, and they abound in the mouth and in the follicles and glands.” Dr Eberth, of Zurich, states that he has found on ordinary sweat small oval-shaped bacteria which are frequently united in strings of two or three, and endowed with rather active movements. The author thinks that they very likely conduce to produce certain chemical modifications of sweat. Drs Ferrier and Sanders on appear to have satisfactorily proved that fungi are not developed from micro zymes, and that their apparent a ociation is one of juxtaposition only. They give the following reasons for adopting this conclusion:—(1) The quick appearance of torula cells in Pasteur’s solution whenever it is exposed to the air, and the rapid development and luxuriant fructification of the higher form ( penicillium ) show that so far as the chemical composition of the liquid is concerned, there exist in it all the conditions favorable to the proce . (2) When precautions are taken to prevent contamination by impure surfaces or liquids, the development which ends in penicillium goes on from first to last without the appearance of micro zymes. (3) Whenever it is po ible to impregnate the test-liquid with micro zymes, without at the same time introducing torula cells or germs, the development of the former begins and continues by itself without any transformation into the latter. Thus fungi are not developed, notwithstanding the presence of micro zymes in the same liquid in which, micro zymes being absent, but air having acce , they appear with the greatest readine . As we have already seen the germs of bacteria exist largely in air; the experiments of Hiller, of Berlin, would seem to negative the theory of Ferrier and Sanders on, as they tend to show that bacteria have little influence on putrefaction. We are indebted to Dr Lionel Beale for these illustrations, which are taken from his very interesting work on ‘Disease Germs.’ IMG:596405606043057898_i241.png: Hiller’s experiments tend to show that putrefaction is independent of the presence of bacteria, that bacteria can develop in liquids such as urine without producing its decomposition, and that the degree of their development and the rate of their multiplication depend upon the amount of a imilable material. The following is the definition given to the word ‘micro zyme’ (which occurs above) by its originator, Dr Sanders on: “I proposed the word ‘micro zyme’ as a convenient general term for the first organic forms which present themselves in organic nitrogenous liquids when about to undergo spontaneous decomposition.” From the experiments of Béchamp it appears that under some circumstances the mother of vinegar, a conglomeration of micro zymes, can be transformed into bacteria, and under other circumstances into a cellular ferment which can excite normal alcoholic fermentation in cane sugar. Subsequent researches have shown that the converse of this is also true, and that the cellular ferment may be transformed into micro zymes and bacteria. A mixture of starch and yeast kept at a temperature of 24° to 35° soon liquefies, and the yeast undergoes remarkable changes. The cells swell, become transparent, and gradually disappear. Myriads of micro zymes of great agility spring into existence, then vibrios appear, and as these increase the micro zymes diminish. The vibrios in their turn are succeeded by myriads of bacteria, and finally the bacteria disappear, leaving nothing but micro zymes, single or coupled together. During these changes a small quantity of gas is disengaged, no butyric acid is formed, and but little acetic or lactic acids. As then the mother of vinegar when changed into bacteria becomes lactic or butyric ferment, and when transformed into cellular matter becomes alcoholic ferment, and as beer yeast becomes lactic or butyric ferment when reduced to micro zymes, vibrios, or bacteria, it is evident that the property of being a ferment of any particular nature does not depend e entially upon the nature of the ferment, but upon its organisation or structure. A contributor to the ‘Medical Times and Gazette’ of February 2nd, 1878, advances the opinion that many of the bacteria are only parts of a plant which has other forms and other modes of growth and propagation when not confined to the living organism or to fluids, and regards the bacterium as a transitional or provisional and not as a permanent form, but an abnormal phase of life thrust upon the plant by accident.