Page:The Journal of Indian Botany, Volume III.djvu/58

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THE JOURNAL OE INDIAN BOTANY. but definitely single. These threads then straighten out into smooth threads, with few or no vacuoles remaining. It is in these single threads that the true split appears, probably larger by the formation of entirely new vacuoles. The splits become more definite, and the anastomoses between two half chromosomes give the familiar ladder-like appearance, often interpreted as “ paired” or “ divided chromatin granules.”

The conclusion is that the longitudinal split appearing during theiprophase cannot be connected with any phenomena of the preceding telophase, but occurs de novo. Therefore any theories, no matter how simple and attractive, which consider the paired threads of the heterotype prophase as the re-appearance of an old split in single chromosomes would be based on a false premise* The figures accompanying the paper amply bear out the author’s conclusions.

Mitchell, Miss M. M. Kesearch on Macrocystis, The following is taken from the published account of a paper read before the Linnaean Soc. London, on January 19, 1922.

Dr. E. Marion Delf gave an account of research on Macrocystis by Miss M. M. MICHELL and herself. After describing the distribution of the alga, the authors reviewed recent accounts of it, and showed lantern-slides in explanation.

The fertile fronds are completely submerged, smooth, dichotomously branched and usually borne on special shoots. They bear sori on both sides of the frond. Exceptional cases were described of discontinuous sori occurring in the grooves of fronds with wrinkled surface and borne on the long swimming shoots, and usually without a swim bladder at the base.

The zoospores do not appear to have been previously described. Material brought from the shore in the morning, and examined in the laboratory in the evening, showed swarming zoospores; the next morning swimming actively, and more slowly.

Cultures were made from the material in the following way: — About 2 hours after gathering, the alga was placed in a covered glass dish, with a few cover-slips at the bottom, and then sea-water was added. The piece was removed the next day, and 10 days later all the zoospores had come to rest, but showing no sign of germination. Five weeks afterwards short filaments of two different sizes were observed, comparable with the male and female gametophytes in Laminariacese reported by Sauvageau and Lloyd Williams. Two months later young stages of the sporophyte were visible on the cover- glasses, a thick-waiied empty cell always being at the base of the sporophyte, probably the empty oogonial wall after the escape of the oospore. No sign of the antheridial cells has been noticed. The discovery of the filaments developed from the zoospores and the subsequent growth of the sporophytes from filaments brings it into line with other members of the same family.

The authors consider that the species occurring at the Cape is Macrocystis angustifolia, Bory, from its rhizome-like attachments.

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