. Elements of biology; a practical text-book correlating botany, zoology, and human physiology. Biology. FLOWERLESS PLANTS 161 Formation of Zygospores. —Two hyphae which are close-lying put out threads which communicate. The end of each of the threads cuts off a cell, and the two cells, each from a different hypha, flow together and mingle. In this condition they remain as a single resting cell. This cell, which puts a heavy wall around itself, is called a zygospore. In the process we called fertilization, we found that the two cells which united to form one cell were of dif- ferent sizes. Her
. Elements of biology; a practical text-book correlating botany, zoology, and human physiology. Biology. FLOWERLESS PLANTS 161 Formation of Zygospores. —Two hyphae which are close-lying put out threads which communicate. The end of each of the threads cuts off a cell, and the two cells, each from a different hypha, flow together and mingle. In this condition they remain as a single resting cell. This cell, which puts a heavy wall around itself, is called a zygospore. In the process we called fertilization, we found that the two cells which united to form one cell were of dif- ferent sizes. Here the cells are of the same size. When two cells of the same size unite to form a single cell, we call the process conjuga- tion. The ultimate result of the conjugation of the two cells is that a new plant grows from the zygospore after a period of rest. During the resting stage a b the spore may undergo veiy unfavorable condi- tions, even to extreme dryness, heat, or cold. The use of the zygospore to the plant is evidently to continue the species during an unfavorable time in the life history of the plant. The pro- cess of conjugation is probably a sexual process. Its significance is not well under- stood.^ Is there then an alternation of generations in the mold ? Physiology of the Growth of Mold. — Mold, in order to grow rapidly, evidently needs considerable moisture and heat. It ob- tains its food from the material on which it lives. This it is able to do by means of digestive ferments, which are given out by the rhizoids or rootlike parts of the hyphae, by means of which the mold clings to the bread. These digestive ferments change the starch of the bread to sugar, and change the proteids into a form that can be osmosed into the hyphae. Thus the plant is enabled to absorb the material. The foods are then changed into. Conjugation of black mold; A, B. (', D. successive stages in the formation of the zygospore. * It seems to have been proved recently that zygospores are f
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