Author Description

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1891 Excerpt:...filament from which a zoospore, sp, is just escaping. B.--The zoospore after coming to rest. C. D, E, F.--Stages in the development of the Vaucheria plant; w, rhizoid; og, oogonium; h, antheridium. and oogonia goes on during the night, beginning in the evening, and being complete in the following morning. Fertilisation ensues during the next few hours. The swarm cells also are formed during the night, and escape in the morning. PRACTICAL WORK. Obtain some of the green Felt to be found on pots in conservatories: select rather a large, old patch, and carefully tease it out in a drop of water. Examine the filaments, and make out the structure described above, first under low and then under high power. The protoplasm and cell-wall can be distinguished more readily after treatment with 2 per cent. salt solution. The nuclei can only be seen after careful staining. Examine the antheridia and oogonia in detail. Watch for the escape of the antheridzoids. To observe these and their cilia, treat with iodine. If possible, examine a series of specimens showing the development of antheridia and oogonia from their origin as simple branches till the process of fertilisation is complete. Since this takes place at night it must be studied in the daytime by means of a series of prepared specimens. Look out for older examples to see the changes which take place in the oospore after fertilisation. To find swarm spores, place a mass of Vaucheria in water and expose it to light. Early next morning, after the night's darkness, examine it. (If this is inconvenient, put it in a cupboard for the night, and keep it in the dark till it is wanted.) Some of the filaments will be seen with a lens to have swollen, rather dark-coloured ends. Mount these very carefully, and observe as above....