BOTANY. 29 



fissiparous division of an ori<:;iiuil cell called the pollen utricle. The pollen 

 grains fall out either singly or united in definite number : sometimes the 

 entire mass is combmed by viscid matter into conglomerations called pollinia. 

 Such is the case in Orchidacese ; here each mass has a prolongation or stalk 

 called a candicle, which sometimes adheres to a prolongation at the base of the 

 anther called rostelbim. by means of a viscid matter termed retiitncitliim. 

 The part of the column in Orchids where the stamens arc situated, is some- 

 times termed cUnnndriuin. 



The mature pollen grain has an external covering called e.vthie, and one 

 internal, intinc. Within these coverings is contained a granular semifluid 

 matter termed fovilla, and composed of small spherical granules sometimes 

 3Ö0ÜÖ of ^11 ii^ch in diameter, together with larger covpuscules which are 

 said to exliibit apparently spontaneous movements. The pollen grains tj^em- 

 selves vary from 3^^ to ^^0 of an inch in diameter, and exhibit highly diversi- 

 fied forms. This form is much altered b}^ the application of moisture. This, 

 when applied to one side, causes the intine to project outwards and form what 

 is called a polleti tube. 



Cryptogamic plants exhibit certain organs, supposed by some to represent 

 stamens, and known as authendia or pollinaria. These are closed sacs, 

 developed in various parts of the plant, either at the surface or concealed in 

 its tissue. The contents of antheridia consist of utricles inclosing peculiar 

 bodies which have been termed phytozoa^ and exhibit active movements 

 at certain periods of existence, when they have been taken for infusorial 

 animalcula. 



The Disk. By this term is to be understood whatever intervenes between 

 the stamens and the pistil. The forms under which it is presented are those 

 of hairs, scales, glands, &.c., often containing saccharme matter, and forming 

 a so-called nectary. The disk may be formed by the degeneration and trans- 

 formation of the stamens. 



The Pistil occupies the centre of the flower, being surrounded by the 

 stamens and floral envelopes. It constitutes the innermost whorl, and is the 

 female organ of the plant, Avhich, after flowering, is changed into the fruit, 

 and contains the seeds. Sometimes it is called the gynmciimi. It consists 

 essentially of two parts, the ovary or germen, and the stigma, which is either 

 sessile (seated immediately upon the ovary) or elevated on a stalk called the 

 style. The pistil, like the other organs, consists of one or more modified 

 leaves called carpels. A pistil consisting of a single carpel is simple; 

 otherwise, compound. Each carpel has its special ovary, style (when 

 present), and stigma, and is formed by a folded leaf whose upper surface is 

 turned inwards towards the axis, the lower outwards ; one or more buds 

 called ovides being developed at the margin. The ovary then represents the 

 limb or lamina of the leaf. The style is generally cylindrical in form, 

 and is traversed by a narrow canal, in which there are some loose 

 projecting cells forming the conducting tissue, as also elongated tubes at 

 the period of fecundation. The stigma is a continuation of the cellular 

 tissue in the centre of the style, and may be either terminal or lateral ; 

 in the Orchidaceae it is placed on a part of the column called the 



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