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Published online by Cambridge University Press: 17 January 2013
The extraordinary processes developed in connection with the base of the suspensor in the common Indian Cress (Tropæolum majus) have long excited the interest of vegetable embryologists, and have led to the publication of numerous observations on the embryogeny of that plant. As the following remarks are interesting chiefly in regard to the peculiar features in which the germs in two other species of the genus differ from that in the common Indian Cress, it will not be out of place for me briefly to recapitulate the principal facts connected with the development in that plant.
page 224 note * Wilson, W., “On the Embryo of Tropæolum majus,” London Journal of Botany, vol. ii. p. 623Google Scholar.
page 224 note † Hofmeister, “Die Entstehung des Embryo,” Leipzig, 1849; Schacht, “Ueber die Entstehung des Keimes von Tropæolum majus, Bot. Zeitung,” 1855, p. 641 (translated in “Ann. des Sc. Nat.” 4e sér. iv. p. 47). In Plate XV. fig. 18, I have given sketches, A after Hofmeister, B and C after Schacht, showing the earlier stages of this germ.
page 224 note ‡ Schacht, l.c. pp. 644–5.
page 226 note * Schleiden (“ Nova Acta Acad. C. L. C. Nat. Cur.,” tom xix. tab. viii. fig. 126) gives a figure of the ovule of T. (Chymocarpus) pentaphyllum, where it would appear that the anatropal character is much more distinctly present, the raphe being of considerable length.
page 227 note * Schacht, , Bot. Zeit. 1855, pp. 641–2.Google Scholar
page 230 note * Schacht, Bot. Zeitung, 1855, pp. 646–7. In Plate XVI. fig. 26, I have given a drawing carefully constructed after figures by Tulasne, showing these cæcal processes in a labiate plant, Dracocephalum peltatum.
page 231 note * As I have elsewhere stated, in a semi-popular lecture on “ Consanguineous Marriages ” (Glasgow Med. Journal, Feb. 1872), the use or function of sexual reproduction, as distinguished from gemmation, seems to be this very obliteration of individual variations, so as “ to keep up an average tone or quality in the species, and, by dilution of individual peculiarities, to eliminate possible sources of evil on their appearance.”
page 232 note * Trans. Bot. Soc. Edin. vol. ix. p. 54, referred to in Masters’ “ Teratology,” pp. 232–3.
page 232 note † The same description applies to the arrangement of the vascular bundles in the above-mentioned abnormal flowers of T. majus.
page 233 note * The amplifications of the figures are, approximately, as follow :—Fig. 1, 45 times linear; Fig. 3, 250 times; Figs. 2, 4-10, and 21-23, 15 times ; Figs. 11-17, 120 times.