. Botany of the living plant. Botany; Plants. 438 BOTANY OF THE LIVING PLANT A section through an infected spot on the Barberry leaf shows the effect of the attack in the greatly increased thickness as compared with the normal leaf (Fig. 337)- The enlarged cells of the mesophyll appear enveloped by fungal hyphae which choke the intercellular spaces. They are massed chiefly at points towards the upper and lower surfaces, to form bodies of considerable size. The first are the flask-shaped spermogonia com- posed of hyphae pointing radially inwards, while from the end of each a minute non-motile s
. Botany of the living plant. Botany; Plants. 438 BOTANY OF THE LIVING PLANT A section through an infected spot on the Barberry leaf shows the effect of the attack in the greatly increased thickness as compared with the normal leaf (Fig. 337)- The enlarged cells of the mesophyll appear enveloped by fungal hyphae which choke the intercellular spaces. They are massed chiefly at points towards the upper and lower surfaces, to form bodies of considerable size. The first are the flask-shaped spermogonia com- posed of hyphae pointing radially inwards, while from the end of each a minute non-motile spermatium is abstricted. These have not them- selves been found capable of causing infection; but they may stimulate development and are possibly male organs {sp). The spermogonia secrete a fluid, sometimes described as " nec- tar " in which large numbers of spermatia may be present. Projecting beyond the spermogonial opening or ostiole are long flexiwus hyphae. The bodies on the lower surface are larger and develop into the cup-like aecid- ium-fruits. Each is composed of an outer sheath or peridium, while the cup is filled with filaments rising from the base, from each of which a chain of aecidiospores is produced. The oldest are distal, and they are shed succession from the downward-. m Fig. 338. Phragmidium violaceum. A, portion of a young aecidium ; st, sterile cell ; a, fertile cells : at a2 the passage of a nucleus from a neighbouring cell is seen. B, formation of the first mother-cell, sm, from the basal turned cups (Fig. 337,*). When ripe ^ $ &\£S££>^ *jSinT they are bi-nucleate. De Bary in 1865 cala!7 celln(z) have arisen ;jm2 the second J j ~> mother-cell. D, ripe aecidiospore ; note Showed that if SOWn On young grass- the paired nuclei. (After Blackman.) (From J ° ° Strasburger.) leaves they infect them, and produce the Rust again. Thus there are two stages in the life-cycle, which differ in host and in propagative organs : the one has paired
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