Book Description

Excerpt from The American Monthly Microscopical Journal, Vol. 10: Containing Contributions to Biology Cover each tumbler with paper to keep out dust but to let in air. Put them away, a set of three in a moist dark place, a set of three in a moist light place. In the pure water, whether in the dark or the light place, two or three days will have produced no change. In the syrup or the cake, from both places, spots of green will have appeared upon the surface. Therefore, mould grows in the dark as well as in the light, and will not grow in water containing no organic matter. In similar ways it may be shown that mould grows well on meat broth and other watery media; that it grows faster in warm places and slower in cold places. 2. Examination with Low Power. - Upon the tip of a needle catch the smallest possible speck of mould, add a drop of water, cover it and place under the low power. There will perhaps appear some very fine threads, but mainly a great dimness with some very dark curved lines. This mount is a failure, proving that water is not a universal mounting medium. That might have been suspected from the water not moistening the film when first tried. Begin again with the needle, and now use alcohol upon the slide. When viewed under the microscope it will appear that the mould is made up of fibres matted together. These will show still better under the high powers. Before using them, mount a new slide in alcohol, carefully teasing the speck of mould before covering it. To tease it, take a needle in each hand, hold down the speck with one needle and pull the mould away with the other one. This separates the fibres for easier inspection. As the alcohol evaporates rapidly meanwhile, some more must be added from time to time, getting it under the cover with a pipette. 3. Under High Power. - The teased speck now appears to be a great complex of fine wavy threads. They make up the large part of the mould, and are called Hyphae (webs) because of their being matted and woven together. These are of two kinds: - (1.) which run indefinitely, many having no cross partitions; (2) which are broken by transverse joints and which terminate in branches tipped with small spheres. Besides these two kinds of hyphae numerous small spheres called conidia will be found in the mount. The hyphae Sand conidia together constitute the mould. The next question is, how are they put together. If a mould growing on a fluid-like broth be carefully examined one can see that it consists of a coat or scum which floats on the fluid, and that from this, called the mycelium hyphae carrying the dust before noticed are borne aloft into the air. These are invisible to the naked eye, but careful examination of bits caught with the needle from such a film convinces you that there are two kinds of hyphae, those of the mycelium and others arising from them into the air. 4. The Mycelial Hyphae. - A single thread from the complex, under medium power, is illustrated in figure i of the plate. Observe the long and narrow, flexuous, and parallel-sided thread or hyphae; that it branches frequently; that these branches are of equal diameter with the main stem; that the stem is not empty but contains something, and that the stem is one continuous tube through all its length and not broken by subdividing cross-walls. The older mycelial hyphae are not one single tube, but, like the aerial hyphae, are transversely divided. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com"