Cytology and Life History of Vaucheria geminata

1. Vaucheria geminata is found most abundantly in the spring and autumn. Sexual reproductive organs are most abundant in September and October; they are also found about April 15. 2. There are one or two periods of general mitosis in the oogonium. The egg nucleus undergoes mitosis just in advance of the vegetative nuclei. 3. The nuclear membrane disappears in both the vegetative and reproductive nuclei during mitosis. Spindle fibers are visible in the vegetative nuclei in the metaphase. 4. The cross wall begins to form about the time the sperm enters the oogonium, and is of vacuolar origin. The vegetative nuclei begin disintegration at the time of fertilization. 5. There is no migration of nuclei either to or from the oogonium of Kaucheria geminata. 6. A swelling forms from the oogonium in the "receptive region," which comes in contact with the antheridium at the time of fertilization. The male element enters through this process. 7. Fertilization occurs during the latter part of the night. Maturation div...