. The Canadian naturalist and geologist. Natural history; Geology. 458 Fresh-Water Algoe of Canada. been noticed by Mr. Bowerbank in a species of Zygnema, which I transmitted to him, and subsequently by myself in a variety of other species. The one is cruciform, and adherent to the inner wall of the cell, (see Fig. 5). It, Mr. Bowerbank remarks, is the vegetable structure which secretes the raphides. They are pro- bably not definite organs, but crystals. The other body is small, elongated, somewhat curved, and attached to or lying upon the plant, (see Fig. 5). This, Mr. B. observes, is certain
. The Canadian naturalist and geologist. Natural history; Geology. 458 Fresh-Water Algoe of Canada. been noticed by Mr. Bowerbank in a species of Zygnema, which I transmitted to him, and subsequently by myself in a variety of other species. The one is cruciform, and adherent to the inner wall of the cell, (see Fig. 5). It, Mr. Bowerbank remarks, is the vegetable structure which secretes the raphides. They are pro- bably not definite organs, but crystals. The other body is small, elongated, somewhat curved, and attached to or lying upon the plant, (see Fig. 5). This, Mr. B. observes, is certainly a string of minute ;— Fig. 5. Cell of Z. nitidum, showing the spiral threads containing spores the cyloblast, and the cruciform raphides. Hass. F. W. Alga, plate 17. We have collected and examined with great care multitudes of these plants—they are to be found in great abundance in almost every stagnant pool—and only in oue instance (Z. curvatum) have we, during a period of two years, observed conjugation in the L. Canadian specimens. "We eagerly looked for it last spring, the time of the year, at which, according to Hassall, it is most usu- ally found in England, and have, up to the beginning of winter, almost every week examined specimens from various localities, and in all conditions of growth, but in no instance have we found conjugation, with the exception noted. We have also failed to discover in any case the cytoblastic organ. A specimen has however been sent us of Z. catenceforme from Paris, C. W., about 360 miles S. West from Montreal, which curiously presents the three forms in which conjugation is some- times found. In the following figure (6) it will be seen that at (a) the contiguous cells are in conjugation, while at (b) it is the contiguous filaments, and that the contents of the opposite cells pass alterately into each other. From these considerations one would be led to infer that these characters are either very evanescent i
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