On the reproduction and supposed existence of sexual organs in the higher cryptogamous plants / by Arthur Henfrey.

  • Henfrey, Arthur, 1819-1859.
Date:
1852
Catalogue details

Licence: Public Domain Mark

Credit: On the reproduction and supposed existence of sexual organs in the higher cryptogamous plants / by Arthur Henfrey. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    mit of its parent cellule in Sphagnum, and then appears as a spiral filament moving freely in water, in fact, as one of the so-called spermatozoa. The pistillidia of the Mosses are the rudiments of the fruit or capsules. When young, they appear as flask-shaped bodies with long necks, composed •of a simple cellular membrane. The long neck presents an open canal like a style, leading to the enlarged cavity below, at the base of which, according to Mr. Valentine*, is found a single cell projecting free into the open space. This single cell is the germ of the future capsule; at a certain period it be- comes divided into two by a horizontal partition, the upper one of these two again divides, and so on until the single cell is developed into a cellular fila- ment, the young seta; the upper cells are subsequently developed into the urn and its appendages, and as this rises, it carries away with it, as the calyptra, the original membrane of the pistillidium, which separates by a cir- cumscissile fissure from the lower part, the future vaginula. These obser- vations of Valentine are not exactly borne out by those of Schimperj* in some of the detail points. According to this author, the lower part of the pistillidium (the germen of Dr. Brown) begins to swell at a certain time, when a capsule is to be produced, becoming filled with a quantity of what he terms “ green granulations.” As soon as the thickness has become about that of the future seta, the cell-development in the horizontal direction ceases, and its activity is directed chiefly to the upper part, which begins to elon- gate rapidly in the direction of the main axis. This elongation causes a sudden tearing off at the base, or a little above it, of the cell-membrane enveloping the young fruit, and the upper part is carried onwards as the calyptra; the lower part, when any is left, remains as a little tubular process surrounding the seta. While the young fruit is being raised up by the growth of the seta, the portion of the recejttacle upon which the pistillidium is borne, becomes developed into a kind of collar, and at length into a sheath (the vaginula) surrounding tlie base of the seta w'hich is articulated into it there. M. Hofmeister j;, again, describes the details much in the same way as Mr. Valentine. He states that there exists at the point where the ‘style’ and ‘germen ’ of the pistillidium join, a cell, developed before the canal of the style has become opened. In those pistillidia which produce capsules this cell begins at a certain period to exhibit very active increase ; it becomes rapidly divided and subdivided by alternately directed oblique partitions into a somewhat spindle-shaped, body formed of a row of large cells. Mean- while the cells at the base of the germen are also rapidly multiplied, and the lower part of the pistillidium is greatly increased in size. The spindle- shaped body continues to increase in length by the subdivision of its upper- most cell by oblique transverse walls, and the opposition which is offered by the upper concave surface of the cavity of the germen, causes the lower conical extremity of the spindle-shaped body to penetrate into the mass of cellular tissue at the base of the germen, a process which resembles the penetration of the embryo into the endosperm in the embryo-sac of certain flow'ering plants. The base of the spindle-shaped body, which is in fact the rudiment of the fruit, at length reaches the base of the pistillidium, and penetrates even some distance into the tissue of the stem upon which this is seated. The growth of the upper part going on unceasingly, the walls of the germen are torn by a circular fissure and the upper half is carried upwards, * Linneau Transactions, vol. xvii. t Recherches Anatomiques et Morphologiques sur les Mousses. Strasbourg, 1848. X Botanische Zeitung, 1849, 798. Botanical Gazette, vol. ii. p. 70.