. Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ . The knee-joint connections of Mougeotiagenuflexa (Dillw.) Ag. [ = M. mirabilis (A. Br.)Wittr.] are deserving of special mention. In north temperate countries this is a commonspecies and although rarely seen in conjugation, contact regularly takes place betweenneighbouring filaments by means of genuflexions of the cells. These knee-joints ofcontact have all the outward appearance of the commencement of scalariform conjugation,but Nieuwland (09
. Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ . The knee-joint connections of Mougeotiagenuflexa (Dillw.) Ag. [ = M. mirabilis (A. Br.)Wittr.] are deserving of special mention. In north temperate countries this is a commonspecies and although rarely seen in conjugation, contact regularly takes place betweenneighbouring filaments by means of genuflexions of the cells. These knee-joints ofcontact have all the outward appearance of the commencement of scalariform conjugation,but Nieuwland (09 A) has brought forward evidence to show that this is not the contact cells appear to be simply glued together and no direct communication isever established between them. Nieuwlands observations indicated that filaments thusconnected very readily break up into their individual cells, and, since this results in an. Fig. 213. A—F, Delarya Hardyi G. S. West. A, conjugating filaments; B—Z), extremities ofgametangia during conjugation showing gradual filling up of internal cavity; E and F, com-pleted zygospores. G—K, D. demitidioiilis W. & G. S. West. G and H, small portions of longvegetative filaments; I, conjugating cells; J and K, completed zygospores. A, E and F,x470; B—D, x940; G—K, x 488. immediate increase in the quantity of Mougeotia, presumably the dissociated cells dividerapidly to form new filaments. Nieuwland regards this knee-joint connection of thefilaments as a phenomenon preliminary to the process of vegetative multiplication. Thephysiological significance of the temporary connection may be an interchange of solublesubstances through the apposed walls of the joint, but the whole question requires detailedinvestigation. In Mougeotia gracillima and M. parvula the chloroplast is occasionally constricted andin several instances the present author has observed two chloroplas
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