Stylar End Research Articles

MEGASPOROGENESIS AND DEVELOPMENT OF MEGAGAMETOPHYTE IN ULMUS

MEGASPOROGENESIS AND DEVELOPMENT OF MEGAGAMETOPHYTE IN ULMUS

INTERNAL DECLINE (ENDOXEROSIS ) OF LEMONS V. CONCERNING THE COMPARATIVE RATES OF WATER CONDUCTION IN TWIGS AND FRUITS

This paper presents the results of a continuation of the studies reported in previous papers on the physiological malady known as internal decline or endoxerosis of lemon fruits (I, 2, 3, 4). Endoxerosis is mainly characterized by a loss of water from the internal tissues of the fruit (I, 2). However, in a very large percentage of instances one of the first visible internal evidences of injury is the presence of gum in the conducting vessels and surrounding tissues, especially in the albedo (white, inner portion) of the peel. When the abnormal physiological conditions persist and become more aggravated, gum becomes more abundant and may be found not only in the peel but in the stylar end of the central axis and may even extend from the inner portion of the peel into the adjoining pulp tissues. A more complete description of this malady may be found in the first paper of this series (i). The production of gum pentoses and pentosans (4) in the fruit materially affects the water-holding capacity of the tissues concerned. Whether in endoxerosis it may also affect the water equilibrium in the tissues of fruit or twig in a mechanical way is to be discussed in this paper and in paper VI of this series, which will appear in the succeeding number of this journal. AUXOGRAPH RECORDS