shining brightly.  In the spring and fall the green stalks of meadow grasses would furnish food, but when these become parched and dry they must either dig after and eat the roots, or search in the stream.  I feel satisfied that they do not tunnel among the roots, for if they did so these burrows would be frequently met with.  Little has as yet been published upon this subject, and that little covers only two spring months—­April and May—­and it would be interesting if those who have an opportunity to watch the species during other seasons, or who have observed them at any season of the year, would make known their results.

RALPH S. TARR

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OUR SERVANTS, THE MICROBES.

Who of us has not, in a partially darkened room, seen the rays of the sun, as they entered through apertures or chinks in the shutters, exhibit their track by lighting up the infinitely small corpuscles contained in the air?  Such corpuscles always exist, except in the atmosphere of lofty mountains, and they constitute the dust of the air.  A microscopic examination of them is a matter of curiosity.  Each flock is a true museum (Fig. 1), wherein we find grains of mineral substances associated with organic debris, and germs of living organisms, among which must be mentioned the microbes.

Since the splendid researches of Mr. Pasteur and his pupils on fermentation and contagious diseases, the question of microbes has become the order of the day.

In order to show our readers the importance of the study of the microbes, and the results that may be reached by following the scientific method created by Mr. Pasteur, it appears to us indispensable to give a summary of the history of these organisms.  In the first place, what is a microbe?  Although much employed, the word has not been well defined, and it would be easy to find several definitions of it.  In its most general sense, the term microbe designates certain colorless algae belonging to the family Bacteriaceae, the principal forms of which are known under the name of Micrococcus.  Bacterium, Bacillus.  Vibrio, /Spirillum, etc.

In order to observe these different forms of Bacteriaceae it is only necessary to examine microscopically a drop of water in which organic matter has been macerated, when there will be seen Micrococci (Fig. 2, I.)looking like spherical granules, Bacteria in the form of very short rods, Bacilli (Fig. 2, V.), Vibriones (Fig. 2, IV.,) moving their straight or curved filaments, and Spirilli (Fig. 2, VI.), rolled up spirally.  These varied forms are not absolutely constant, for it often happens in the course of its existence that a species assumes different shapes, so that it is difficult to take the form of these algae as a basis for classifying them, when all the phases of their development have not been studied.