Our Invisible Friends and Foes: Bacteria

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Our Invisible Friends and Foes— Bacteria

BY J. K. GREAVES, PH. D., BACTERIOLOGIST, UTAH STATE AGRICUL- TURAL COLLEGE

The telescope revealed to the inhabitants of this globe the vastness of the universe, the enormous number, the great size and complexity of the planets which are found throughout space, and the astronomer spends hours studying this complex aggre- gate. On the other hand, the microscope has revealed to us an enormous number of objects, which, before the use of the micro- scope, we knew only by the many changes which they brought atout. In the past these changes have been variously interpreted. We may say that the telescope has revealed the infinitely large, while the microscope has revealed the infinitely small. One group of these minute organisms we have learned to call bacteria another, yeasts; and still another, moulds. They are just as great in number and just as full of interest and importance to us as are those of the infinitely great. The bacteriologist spends his time studying these minute organisms, trying to help the beneficial, but to suppress the injurious ones. To the layman the terms bacteria, microbe, and the like, usu- ally suggest a minute animal, and we often find them referred to as "bugs." If we stop to examine bacteria, we find many of them possessing properties and structure similar to those of ani- mals. They are all devoid of green coloring matter, and for this reason they are compelled to live upon complex foods, as do the animals. Furthermore, many of them have the power of independent active motion. These facts have lent force to the suggestion that bacteria are true animals. But their general form, their methods of growth, their formation of threads, and spores, and their similarity in general to the lower forms of plants, have caused the biologists to place them in the class with the plants. So we should consider them as the simplest and most minute forms of plant life found upon this earth. Because of the absence of the green coloring matter, they are often spoken of as colorless plants. We must not, however, consider them as being abso- lutely without color, for they may be violet, blue, yellow, orange, red, gray, white, or any of the other colors. In shape, bacteria have the very simplest conceivable struc- tures, and although there are thousands of different kinds of bacteria, differing in properties, they all have onlv three general

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forms. The rod-shaped organisms, which may he compared to a lead pencil. They have a round end in some cases, in others it is straight, while still others have the ends hollowed out. The size also varies,some being so short that it is next to impossible to tellwhether they are rod or merely round organisms others are ;

comparatively long. Another form of bacteria is the spheres, and they may be likened to a ball, or at times, to an egg. They may be large or small, and group themselves in various ways. The third type are spiral, and may be likened unto a corkscrew. In these, the spiral may be loosely or tightly coiled, or there may be one, two, or many, coils. Then there may be great variations within the same group, as some of the rod-shaped organisms may appear as clubs many times larger than the average, or they may appear as crosses, stars and the like. The formation of large club-shaped organisms is very characteristic of the organism which causes diphtheria, while the formation of crosses, stars, and the like, is characteristic of the organism which grows in the roots of, alfalfa. They have been considered as the lame and halt in the human species. This, however, is hardly an apt illustra- tion, for these peculiar-shaped organisms have all of the powers that the others have, and if they found their way into the body of an animal, they would be just as likely to produce the disease which is characteristic of the organism as would the ones with the normal shape. While there is a great variation in the size of bacteria, all are extremely small, and even the largest are not visible to the naked eye. the smallest are beyond the range of our most power- ful microscopes, while others appear as mere dots. The bacteria which cause influenza are rod-shaped organisms, and if they be placed end to end, it would take fifty thousand of them to reach one inch, or it would require about fifteen thousand of the bacteria which cause typhoid fever to form a line one inch in length. Of the very largest known, it would require seven thousand to reach an inch. We often magnify bacteria one thousand times and then they appear as dots under the microscope, but if we should magnify a man to that extent he would appear to be six thousand 5

feet tall and fifteen hundred feet wide. Bacteria are so small that at times we find five millions in a small drop of milk, and yet they have plenty of room to move about, for it would require twentv-five hundred million to weigh the same as a drop of milk. You may wonder, if bacteria are so small, how they can bring- about such enormous changes, for it takes but a short time for them to tear down the body of a large animal that has died, and you all know how fast various plants and fruits decay under appropriate conditions. Decay is due to bacteria. One organism could of itself bring about only a small change, but they multiply with almost inconceivable rapidity. The rod-shaped organisms

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grow until they have reached a certain length, they then divide into two, an these in turn grow to maturity and then divide. 1

Some of them may remain linked together, hence they appear to us as long chains of hacteria. In the case of the spherical or- ganisms, they may divide into two and remain linked together, thus giving the appearance of a string of beads. This is the characteristic of the common blood poison organism. Other spherical-shaped organisms give rise to four on each division, and when they remain connected together and great masses are formed, they resemble a bunch of grapes. This is a property of, the common boil-causing organism. Still another of the spherical organisms gives rise to eight on each division and they appear very similar to a bale of cotton. This is a characteristic of many of the organisms found in air. It has been estimated that if bacterial multiplication went on unchecked, the descendants of one cell would in two days number 281,500,000,000 and that in three days the descendants of this single cell would weigh 148,356,000 pounds. And it has been further estimated, by an eminent biolo- gist, that if proper conditions could be maintained for their life activity, in less than five days they would make a mass which would completely fill as much space as is occupied by all of the oceans on the earth's surface, supposing them to have an average depth of one mile. Even in the face of these facts one need not fear, for bac- teria have been on this earth, and have been multiplying, prob- ably long before the advent of man, and the earth has not been filled by them. This is due to there being a struggle amongst them, just as there is amongst higher plants and animals. One knows that if wheat be sown too thick, none of it will mature. Sometimes it is a lack of food, other times a lack of sunshine still others, a lack of moisture which prevents the growth. So it is with bacteria, the food or water may give out, but more often

it is the products which they form which prevent them from con-

tinuing to multiply. When these adverse conditions arise, many bacteria have the power of mobilizing the vital particles of their body into much smaller space than they occupy during their nor- mal life. They exclude all of the excess moisture and surround themselves by a tough resistant coat. In some respects this form of the organism resembles the seed of the higher plant, and we speak of it as the spore. While in this stage, they will withstand many conditions which would quickly prove fatal to the growing bacteria. Some of them while in this condition can with- stand the temperature of boiling water for many hours, or they may survive the treatment with strong carbolic acid. They, for the time being, have lost the power of multiplying, but they are still alive, and if they be brought into appropriate surroundings they

will change into normal bacteria, just as does the kernel of wheat

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change into the young plant when placed in moist soil. It is indeed fortunate for mankind that but few of the disease-pro- ducing organisms form spores. There are, however, many of the bacteria which cause fruit, meat and various other food pro- ducts to spoil, which do form very resistant spores, and this is why many food products have to be heated for such a long time, or to such a high temperature, to make them keep. At times, in or- der to avoid heating the substance to such a high temperature, the intermittent method of sterilization is made use of. In this method the substance which is to be sterilized is heated to 100° C, for a short time. This heating kills all of the organisms which are not in the spore form. After standing in a moderately warm place for twenty- four hours, during which time the spores start to grow, it is again heated for a short time, thus killing the others which

have started to grow. Often this is repeated even a third time before the vegetable or other products are canned. The manner of formation of the spore within the body of the organism is intensely interesting, for it varies with different species. The bacteriologist has devised means whereby he can color the body of the organism one color, and the spore within that body a different color. If we color the various organisms just as they are in the first stages of spore formation, in some we find the little red dot situated within the centre of the blue body. In others we find it in the centre, but the spore is much wider than the body of the organism, hence we have a boat-shaped or- ganism. In still others the spore forms at the end and gives to the organism the appearance of a drum stick. This is the case with the organism which causes that dreadful disease lockjaw. If one places a small handful of hay in a bottle containing some beef tea, and allows it to stand in a warm place for twenty- four hours and then examines a drop of it under the microscope, it will be found to be filled with living organisms. One notices that all of the particles within the drop are moving, even the small particles of hay. But there is a great difference in the way in which they move, some swing back and forth but others are seen to move swiftly across the field and out of sight. All of the bodies which are thus seen to move rapidly are bacteria which have the power of movement. By appropriate methods it has been shown that these bacteria which have the power of inde- pendent movement have on their bodies long hairlike appendages. In some they are many times the length of the body of the organ- ism's and may be situated at one or both ends, or they may even surround the entire body of the organism. It is by the striking of the water with these whip-like appendages that the organisms are able to move. As one examines moving bacteria under the microscope, one would think that they were moving with the speed of an express train, but on actually measuring their speed,

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618 IMPROVEMENT ERA we find that to be an illusion. The cholera organism has been known to attain for a short distance the enormous speed of eight inches per hour. So we need not fear that they will overtake even the slowest of us by their own means of locomotion. But they have a more rapid and safer way of passing from place to place. Many of them use the common housefly as their airship, others the bedbug, while still others will chance a ride with the flea. At other times they find their way into food or onto clothing, and are transported from place to place. Some are picked up with the particles of dust, but to the disease-producing organism this method of travel is much more fatal than is the modern airship to man. The spore forming organisms may, however, make the journey in this manner with a fair degree of safety. It is not •because the fall would hurt these specks of living matter, but when struck by the direct rays of the sun they are killed in a very short time. Many of them cannot withstand even diffused sunlight for any great length of time. So we find that sunshine not only furnishes us with all the energy which we get from our food, but it is probably the greatest protection we have against disease germs. But many of them could not have made the journey any great distance even in the dark, for their bodies are about ninety percent water, and if not clinging to some moist substance they would soon lose sufficient moisture to cause death. Many of the disease-producing organisms are found in the mouth, sometimes in individuals apparently healthy, and they can safely make the journey from the lips of one to the lips of another, on the common drinking cups. The fingers are continually find- ing their way to the mouth, and if the saliva was indigo what a blue world it would be indeed. For we find, "The cook spreads his saliva on the muffins and rolls the waitress infects the glasses ;

and spoons the moistened fingers of the peddler arrange his fruit ;

the thumb of the milkman is in his measure the reader moistens ;

the pages of his book; the conductor his transfer tickets; the 'lady' the fingers of her glove. Everyone is busily engaged in this distribution of saliva, so that the end of each day finds this secretion freely distributed on the doors, window sills, furniture and playthings in the home, the straps of trolley cars, the rails, counter and desks of shops, and public buildings, and indeed upon everything that the hands of man touch ;" and in many cases, with it, the germs of many of our diseases. If the next comer has not learned that the hands are to be kept from the mouth, he can easily transfer to his mouth, disease germs, and if, perchance, they find suitable soil, the individual soon finds him- self suffering with a disease. It might be a mild attack of lagrippe or a fatal attack of tuberculosis. It is often the case in the home or the hotel that the organisms are transferred from one dish to another bv the common dish cloth or dish towel.

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They are not, contrary to the common conception, conveyed in the breath, but they may be carried several yards in the fine crops which are forced from the mouth in speaking or cough- ing. So we find that bacteria have many ways of being trans- ported from place to place, and from individual to individual, but if we remember what a great friend the sunlight is to us, an 1

that practically all diseases are caught by direct contact, we can avoid many of the diseases to which the human species are heirs. LOGAN, UTAH

Appraised

They call him a fool For not striking back- When he was oppressed; But they never guessed That the strain of the rack Was his portion within Suppression meant strength, To retaliate, sin. Was he rightly appraised? They christened him "sis," For refusing to go To the haunt where, I ween, There never was seen A man who would grow In the image of Him Who gave the command, "Abstain from all sin." Was he rightly appraised? They thought her unkind That she did not weep When God sent release With seal of his peace. The last dreamless sleep: But well did she know How welcome the summons Ofttimes is to go. Was she rightly appraised? Think not that the fount Of these souls ne'er shed Their measure of tears: Unseen each heart bled, 'Neath burden of pain, A victor o'er self, They won the world's bane. Were they rightly appraised? Grace Ingles Frost