CONIFER.E. .^r. 



which it terminates in a roundish apex (Fig. 316 /). The Taxine^ and most 

 Cupressinece and Araucarieae have two opposite cotyledons, although in some 

 CupressincDe there are from three to nine, and in some Araucarie^ whorls of four 

 cotyledons ; while among the Abietinese there are rarely so few as two, more often 

 four or even as many as fifteen. To refer this larger number of cotyledons to the 

 division of two opposite ones, as Duchartre proposes, is entirely opposed to the other 

 processes of leaf-formation in these plants, especially to the common occurrence of 

 whorls consisting of several leaves on the growing axis of seedlings. 



When placed in damp soil the endosperm swells up, bursts the testa at the 

 radicular end of the embryo, which is then pushed out by the elongation of the axis, 

 and grows into a strong descending tap-root, from which lateral roots proceed, suc- 

 ceeding one another rapidly in acropetal succession, and subsequently branching. 

 This is the commencement of the root-system of Conifers, which is frequently 

 strongly developed and persistent. After the emergence of the root, the coty- 

 ledons elongate in their turn, push out their bases from the seed and the end of 

 the axis that lies between them ; but they themselves remain in the endosperm until 

 it has been absorbed. In Araiicaria brasiliensis the hypocotyledonary portion of 

 the axis remains short, and the cotyledons remain contained in the seed ; in most 

 Conifers, on the contrary, this portion becomes greatly elongated, making a sharp 

 bend in an upward direction, pierces the soil, and draws the cotyledons with it. 

 As soon as these are exposed to light, the hypocotyledonary portion straightens 

 itself, the whorl of cotyledons expand, and, having become green while still 

 underground, act as the first foliage-leaves of the seedling, the apex of its axis having 

 in the meantime formed a bud with new leaves (Fig. 316). 



I\Iodc 0/ GrocVlh and External Differentiation. The terminal bud of the stem 

 of the seedling grows more rapidly, though frequently interrupted, than the lateral 

 shoots which arise subsequently. The primary stem is thus a direct prolongation of 

 the axis of the embryo ; it never ends in a flower, but grows indefinitely at the 

 summit, becoming thickened to a corresponding extent by the activity of a cambium- 

 ring, and thus becomes a slender cone attaining a height of 100, 200, or even 

 more feet\ and a diameter at the base of 2 or 3 or as much as 20 feet. On this 

 highly-developed primary axis the lateral axes of the first order are produced ; 



Mohl, Vermischt. Schrift. pp. 25 and 49. — Schacht. Lehib. der Anat. u. Phys. vol. II. p. 433. — Eichler 

 in Flora 1863, p. 530 [and Nat. Hist. Rev. 1864, pp. 270-290; Fioia 1873, and Trans. Bot. Soc. 

 Edin. 1873. pp.535 -541. — Dickson, Trans. Bot. Soc. Edin.VI, p. 420; New Phil. Journ. i86r, pp. 198, 

 199. — J. D. Hooker, On the Ovary of Siphonodon in Trans. Linn. Soc. XXII, pp. 137, 138. — Caspary 

 in Ann. des Sci. Nat. 4th series, vol. XIV, p. 200, and Flora 1862, p. 377. — Brongniart, Bull. Bot. Soc. 

 France XVIII, p. 141.— Van Tieghem, Ann. des Sci. Nat. 5th series, vol. X.] For the fertilisation, 

 Hofmeister in Vergl. Unters. 1851 [On the Germination, Development, and Fructification of the 

 Higher Cryptogams, Ray Soc, pp. 400-433]. — Strasburger, Die Befruchtung der Coniferen, Jena 

 1869. For the pollen, Schacht in Jahr. f. wiss. Bot. vol. II, p. 142.— Strasburger, Ueber die Bestiiu- 

 bung der Gymnospermen, Jenaische Zeitschr. vol. VI. Also in addition : [Zuccarini, Morphology of 

 the Coniferee, Ray Soc. Rep. and Pap. on Bot. 1845.]— Pfitzer, Ueber den Embryo der Coniferen, Neider- 

 rhein. Ges. fiir Natur. u. Heilk. Aug. 7, 1871.— Reinke, Ueber das Spitzenwachsthum der Gymnosperm- 

 Wurzeln, GGttinger Nachr. 1871, p. 530 —[Strasburger, Die Coniferen u. die Gnetaceen ; eine mor- 

 phologische Sludie, Jena 1872.— Eichler, Sind die Coniferen gymnosperm oder nicht? Flora 1873.] 

 ^ [The trunk oi Sequoia (Wellhigtonia) gigantea of California attains the height of 400 feet.— Ed.] 



