. Botany of the living plant. Botany. Fig. 325. Fucus. A, oogonium, the contents of which have divided into eight eggs, li oogonium, from which the contents (C) have been 1), H, liberation of the eight eggs ; s/= stalk ; «;«^middU^—^nrf = inner layers of the fmgonial (After Thuret.) (From Strasburger.) The solitary oogonia, with their few ova, find their biological cluciilation in the facts that the ova are large, and have a strong chciiy tactic inrtucncc on the rnotile spermatozoids. Their size gives a high degree of certainty of successful germination if once fertilised. The
. Botany of the living plant. Botany. Fig. 325. Fucus. A, oogonium, the contents of which have divided into eight eggs, li oogonium, from which the contents (C) have been 1), H, liberation of the eight eggs ; s/= stalk ; «;«^middU^—^nrf = inner layers of the fmgonial (After Thuret.) (From Strasburger.) The solitary oogonia, with their few ova, find their biological cluciilation in the facts that the ova are large, and have a strong chciiy tactic inrtucncc on the rnotile spermatozoids. Their size gives a high degree of certainty of successful germination if once fertilised. Their attractive influence .•wxures a high probability of fertilisation, notwithstanding their immobility, which has followed on increase in size. But Fucus is not the last term of the scries of reduction of the oogonium. In Ascophylhtm only four ova are matured in each, in Pelvetia two, and in Himaiithalia and others only one. Vestigia of the atrophied eggs are found, which clearly indicate that their numU-r has been reduced. Thus the Brown Algae form a coherent series of difterentiation. Their sexual cells probably originated from motile roos{K:)res. all alike. The first functional though not formal distinction of sex is seen in Ectocarpus siliculosus (Fig. 321), and confirmed by diflerence of sire ol the gametes in E. secundiis (Fig. 322). Steps in loss of motilitv are seen in thcv plants, and in Cutleria (Fig. 323). while in Fucus the large ovum is entirely non- motile (Fig. 325). Finally, in Hii)innfhaila it occupies the whole oogonium : 2 15. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Bower, F. O. (Frederick Orpen), 1855-1948. London, Macmillan
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1919
