ee IVC a Ne i b | n= 2-12 aE f | ‘ Bacteria of water. rat ‘ ©. P. West. 1896. eee Wee KeaLM Wels K, NOMA IS SNM RAR AAS THESIS oye - ~~ — -; T-H-E-S-tI-S i- on -: B A C T E RI A O F W AT E R i- O. P. West. Aurust 8th, 1896, BACTERIA OF WATER, The world of bactszria was first discovered in the latter part of the sixteenth century. Not withstanding its vast importance and extent, no especial attention was paid to it for years after its discovery. No one was able to see any use to which these minute organisms could be put, neither could anyone comprehend any damarfe they could possibly do. So longs as this was the case science was willing to let them \ exist, merely, as curiosities. But some bold thinkers, vecoming dissatisfied with the explaination of the causes of certain descases, argued that these microbes might be looked to as a source of many maladies This idea was first received with considerable opposition, but it gradually gained favor,year after year, and today nearly all scientists are ready to accept it. It would, however, be altogether wron;; to desire the destruction of all bacteria. Indeed, it is claimed that they are more beneficial than harmful. As they are necessary to plant growth, their destruction would be ours as well. Bacteria may be defined to be single-celled microscopic plants. It is rather difficult to think of a plant's being able to move about from place to place, but many of these plants are as motile as any of the members of the animal kingdom. In size they vary very much, but none are visible 10408:;3 ~2- without the aid of a microscope. There are many species for which a square inch of surface would be ample space for six hundred million of the germs. These little plants may be found almost everywhere that life can exist. A ftandful of soil, a breath of air, ora swallow of water may contain millions of them. There re, however, a few places where they have never yet been discover- ed. It is claimed that they never intrude any considerable distances above or below the surface of the earth. The atmos- phere of mid-ocean is also said to be free from them. The classification of bacteria is done in a variety of ways. Some are known by their form, others by the material from which they derive their sustenance, others by their mot- ility or non-motility, others by their ability or inability to produce desease, and still others by their behavior in certain culture media. The principal basis of classification is according to their form. There are three recognized forms, viz: The mlobular, or micrococci; the rod-shaped, or bacilli; and the screw-like, or spirilla. The behavior of bacteria in different culture media is a favorite method of analysis to which the bacteriologist resor ts. This method enables one to detect many characteristics which could not be determined in any other way. Of the bacteria procured from the various sources, none perhaps, are more interesting to study than those found in water. The microbes which cause the dreaded deseases of typhoid fever and cholera are disseminated by means of drink- ing water. River water produces a bacterium which produces a beautiful violet color and which will cnange solid geletine into a liquid form. There is also a bacterium which changes water into a red colored material. A microscopic examination of this variety shows it to be very active. It darts across the field from side to side, as though it were trying to escape from some devouring foe. On July 17th, the investigation of a waterbacterium was commenced. An ordinary agar plate-culture of some drinking water was made. To make a plate-culture a glass plate is pleced in an iron box and this is put into a dry-air-steriliz- er. The sterilizer is kept at a temperature of 170 degrees cents grade for one hour. The object of this process is to kill all bacteria which mi cht have been on the plate. A moist-chamber, which consists simply of a glass dish with a cover, is then procured, This dish should be about six inches high and fifteen inches in diameter. The next step is to place a rlass bench into the moist=chamber. Upon this hench, the sterilized glass plate should be placed. The agar, having ben previous put into a sterilized test-tube corked with a cotton plus, it is then melted by means of a water~bath. The medium is afterwards inoculated with the water by the use of a sterilized pipette. The mouth of the test-tube is then sterilized by rotating it in the flame of a bunsen-burner. When the mouth of the test-tube has suffic- lently cooled, its contents is poured upon a gflass plate. The moist-chamber is then covered and the bacteria are left to develope their colonies. Glass plxntes and benches may be arranred one above another in such a way thet three cultures may be made at the srme time. On July 22nd, the plate-culture had developed several thrifty looking colonies. Two of these colonies were especi- ally conspicuous, one being white and tine other of a brown color. They were both of a circular form and each was ahout one-fourth inch in diameter. It has been found that all the bacteria of a colony are the offspring of a single microbe, so the members of each individual colony must all belon;; to the sme species. The bacteria of these colonies were com- pared uncer the microscope and it was found that there was no perceptible difference between them. They were both mic- rococci, Thus it may he seen that the color of colonies can not always be depended upon as a means of classification. On the sme day a pure culture was made by transplanting Some bacteria from one of the above described colonies into some plycerene arar. This ::oterial is prepared by addiny;; glycerene to ordinary agar. It was contained in a sterilized test-tube. To transplant the bacteria, a sterilized platinum Wire fused into the end of a ;:lass rod was used. The pure culture was exumined the next day and it was Observed that the microbes had been busily at work. They hai formed several colonies and had chanced about one-third of the glycerine agar from a solid to a liquid form. A hanging drop exanination showed these germs to *e Slowly motile. It took them over an hour to distribute them Selves evenly through tiie drop. They scemed to have a ten- dency to move ahout in pairs, tnoush a few sin ;le ones were observed. To prepare a hangin; drop for examinntion a small drop of distilled water is placed unon the center of a cover-slass, The drop is then inoculated with a specemin to he examined, A concave slide is procured and vaseline is smeared around tie edges of tiie concave surfnce, for the p rpose of holdin; tiie cover glass in place. The coOver-glass is then inverted over the concave surfsce and the specemin is ready for examination. A petrie-dish culture of some river water was meade on July 20th, These petrie dishes are mde of plass, they ::re Circular in form and are about one-half ineh thick and three and one-half inches in diameter. The cover laps down over the sides of the dish in such a way as to prevent the bacteria from entering it when the cover is in place. It is necess- ary to sterilize the dish before using it. After having -6- prepared and inoculated the culture medium the sane as fora plate-culture, it is poured into the petrie-dish. Care should be taken to have the medium evenly spread over the bottom of the dish. The culture medium used in this culture was plycerine agar. Five days after the preparation of the cul- ture it had developed several colonies. From one of these colonies a pure test-tube culture was made. The colony Selected for this purpose was of a yellowish color, circular, and about one-sixteenth of an inch in diameter. Glycerien apar was used for the culture mediun, By the 27th, of July the culture had developed a larj:e number of white colonies and a considerable amount of the medium had been liquified. A microscopic emamination showed these bactcria to be bacilli. The ends of the germs were rounded and they were about one and one-hald times as long as broad. By means of a hanging drop examination they were shown to be very act- ive. Nearly all of them were constantly moving some kept whirling round and round, while others were darting about and appeared to be busily searching for something. It may be © that they were especially fond of the glycerine agar from which they had just been removed, and that they were exploring their new field in quest of some of that material. a omit The above described organisms are only a few forms of the myrids of bacteria which infest the water. This subject contains material for many volumes. It can be hoped of this brief article, merely to call to the readers attention that some of the commonest materials about him may be a field for amost interesting study. MICHIGAN STATE IIHT ITY LIBRAR ‘iil nh tl 3 12 31 || ‘NN 43 19 | | 54