. Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ . dia or gynogonidia, the former giving rise to Voltocese 181 antherozoids and the latter developing into eggs. In V. aureus, which is themost abundant European species, 16 or 32 antherozoids are formed in abundle by the division of the contents of an androgonidium, but in and other species as many as 128 are often formed. By theconversion of the mother-cell-wall into mucilage the antherozoids are atfirst set free in compact circular
. Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ . dia or gynogonidia, the former giving rise to Voltocese 181 antherozoids and the latter developing into eggs. In V. aureus, which is themost abundant European species, 16 or 32 antherozoids are formed in abundle by the division of the contents of an androgonidium, but in and other species as many as 128 are often formed. By theconversion of the mother-cell-wall into mucilage the antherozoids are atfirst set free in compact circular bundles, and are arranged with their longaxes all parallel. Each antherozoid is an elongated cell, pointed at one endand rounded at the other, and the paired cilia may be inserted terminally(F. aureus) or laterally (F. globator). In the male colonies of F. sperma-tosphsera, in which all the cells form sperm-bundles, Powers has observedas many as 65,536 antherozoids (or sperms) all maturing at the same timein one crenobium. The gynogonidia are usually few in number, averaging6 in the colony in V. aureus and 30 in F. globator, but in F. perglobator. Fig. 109. A—C, globtttor (L.) Eluenb. A, section of the peripheral region of colonyshowing a single cell; B and C, surface views, showing (in C) the broad protoplasmic con-nections between the cells. J>, Volvox aureus Ehrenb., median section through part ofcolony. /, inner membrane of wall; o, outer membrane; s, special layer of wall; »i, mucus;ml, middle lamella ; p, protoplast. Very highly magnified (after A. Meyer). from 300 to 400 have been seen in one ccenobiura. They develop intoglobular oospheres, which while still unfertilized attain a diameter of over90 /JL in F. Weismanniana. Self-fertilization is said to take place in , but-this is not the case in several of the other carefully investi-gated species. According to Overton (89) each female colony of F. aureushas a polar plateau/ a slightly rais
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