HYGIENE CHAPTER I BACTERIA BACTERIA is a general term for the lowest form of vegetable micro-organisms. The word "bacteria" conveys to most people only an idea of contagious disease, which is erroneous and unfortunate, because the rôle played by most bacteria is beneficial to man, and the most interesting facts about them are the wonderful part they take in the processes of nature. Before taking up the study of their powers we must first consider their shape, size, habits, and where they are found. Shape. Although there are hundreds of different species of bacteria, there are only three general FIG. 1. b General shapes of bacteria: a, Spherical forms; b, Rod-shaped forms; c, Spiral forms. spirals, which Professor Conn compares to billiard balls, lead pencils, and corkscrews. The spheres may vary in size, the rods in length, and the spirals have one or many coils, but in all of the variations the general form remains spheres, rods, or spirals. |