NTRODUCTION. 



31 



Fig. 29. 



Fig. 30. 



of the receptacle or axis of a flower, &c. For example, in the cherry there 

 are five sepals, five petals alternate with them, but the stamens are twenty, 

 but these may be viewed as forming four whorls with five stamens in each. 

 In the Squill the parts are disposed in threes, here the sepals and petals are 

 normal, but the stamens are six in two rows, the outer one alternate with the 

 petals and the inner alternate with the outer. So, also, by irregularity from 

 abortion, in the Primrose the sepals, petals and stamens are normal as to 

 number, but the latter are opposite the petals instead of being alternate with 

 them ; to account for this, we must suppose a row of undeveloped stamens 

 between those present and the petals ; this is the case in Samolus, which has 

 five small scales or aborted stamens in such a situation. A multitude of other 

 examples might be adduced, but these are sufficient to explain the theory. 



The Ovule is the rudiment of the future 

 seed. Ovules are attached to the placenta, 

 either immediately or by a short stalk, called 

 funiculus or podosperm. They vary in 

 number ; where there is one, it is said to be 

 solitary, where their number is uniform and 

 not numerous, they are said to be definite, 

 where they are very numerous, to be inde- 

 finite. They also vary as to situation and 

 direction with respect to the cavity in which 

 they are contained ; thus they are ascending 



when they are fixed to the placenta above ovary of rhamvia. a calyx, b Ovary. 

 the base, and directed upwards; horizontal c Disk - <* Ascending ovules. 



when they project from the side of the cell ; pendulous 

 when their direction is downwards ; and suspended 

 when they are affixed to the top of the ovary ,and hang 

 perpendicularly. 



The ovule consists of a nucleus, enclosed within two &. 

 sacs called the primine and secundine. Each of these 

 sacs have open mouths ; that of the first termed exos- 

 tome, that of the latter endostome ; these contract as 

 the ovule changes to a seed, and become connected ; the^'^t^LT/zontarovuS" 13 

 small aperture, or the scar indicating its position, is 



termed foramen or micropyle. The sacs and nucleus are distinct and uncon- 

 nected, except at base, where they are confluent, and the point of union is the 

 chalaza. In what may be considered as the typical condition, the two coats 

 and nucleus are connected to each other at the base of the ovule, that is, 

 next the placenta, and the axis is rectilinear, the foramen being opposite the 

 chalaza; such an ovule is called orthotropous ; but it often happens that a 

 change takes place during its growth, consisting either in its complete inversion 

 upon the funiculus, so that the apex is brought down by the side of the stalk 

 and points towards the placenta, when it is termed anatropous ; or the ovule 

 curves upon itself and thus brings the apex near the stalk, in which case it is 

 campylotropous. In anatropous ovules the stalk adheres strongly to the part 

 of the surface to which it is applied, and the ripe seed breaks away at the 

 point where it is free from the coats or skin, to which the adherent portion 

 remains attached. This receives the name of Raphe, and appears in the 

 form of a ridge, passing from the Hilum or scar left by the detachment of 

 the stalk from the seed, to the chalaza. The raphe is only found in ana- 

 tropous seeds, in all others the hilum corresponds to the chalaza, whilst in 

 these they occupy opposite extremities of the seed. 



