INTRODUCTION. 495 



hollow or pitcher-like nectaries (as in Helleborus), or they assume the most wonderful 

 forms, like the petals of Aconitum'^. 



Even before fertilisation, pollination is usually followed by striking changes in the 

 parts of the flower, particularly in the gynaeceum, and especially when the parts con- 

 cerned are delicate; thus the stigmas, style, and corolla wither, the ovary swells up 

 (as in Gagea and Puschkinia), and the like. The most striking result of pollination 

 is shown in many Orchideae, where the ovules are only formed as a consequence of this 

 process. 



[The process of Fertilisation is essentially this, that protoplasmic and nuclear substance 

 passes from the pollen-tube into the oosphere ; the protoplasmic substance coalesces 

 with that of the oosphere, and the nuclear substance {male pronucleus) with that of the 

 oosphere {female pronucleus) to form the definitive nucleus of the oospore.] 



Those changes however which are excited by fertilisation are still more energetic 

 and varied than those which are consequent on pollination ; the oospore developes into 

 the embryo; the endosperm — formed previously in Gymnosperms— is completed in Angio- 

 sperms only subsequently to fertilisation ; the ovules grow along with the ovary, their 

 layers of tissue are differentiated, become lignified, pulpy, dry, &c. The increase in size 

 of the ovary, which is frequently enormous (in Cucurbita, Cocus, &c. several thousand 

 times in volume), shows in a striking manner that the results of fertilisation extend 

 to the rest of the plant, in so far as it affords the materials of nourishment. Striking 

 changes in form, structure, and size take place after fertilisation, especially in the 

 carpels, placentae, and seeds ; but very frequently similar changes result also in other 

 parts. Thus, e.g., it is the receptacle that constitutes the fleshy swelling which is called 

 the Strawberry, on the surface of which are seated the small true fruits ; in the Mulberry 

 it is the perianth of the flowers that swells up to form the succulent coating of the fruit ; 

 in Taxus it is a cup-shaped outgrowth of the axis beneath the ovule (the aril) that 

 surrounds the naked seed with a red fleshy coating, &c. Popular usage includes under 

 the term Fruit all those parts which exhibit a striking change as the result of ferti- 

 lisation, especially when they separate as a whole from the rest of the plant; in ordinary 

 language the Strawberry, as well as the seed of the Yew surrounded by its aril, the Fig, 

 and the Mulberry, are all fruits. Botanical terminology limits the idea of Fruit within 

 narrower boundaries, which, however, are not yet sharply defined. In the most exact 

 use of botanical terms, the whole of the gynaeceum which ripens in consequence of 

 fertilisation may be termed the Fruit. When the gynaeceum consists of coherent 

 carpels or of an inferior ovary, the flower produces a single entire fruit ; if the carpels 

 do not cohere, each forms a part of the fruit, or a fruitlet. This limitation of the term 

 is often, however, inconvenient ; and it would seem preferable to give it a definition 

 which will vary in the different sections. 



The point to be most clearly borne in mind by the student is that the fruit is 

 not a new plant-structure. All the parts of the fruit which are morphologically 

 determinable, originate and assume their morphological character before fertilisation ; 

 the result of fertilisation is merely a physiological change in the parts. The only new 

 parts in a morphological sense are the embryo and the endosperm, which are pro- 

 duced in the ovule. 



The Inflorescence. When a shoot which has previously formed a large number of 

 foliage-leaves terminates in a flower, the flower is said to be terminal ; if, on the other 

 hand, a lateral shoot developes at once into a flower, with one or at most a few bracteoles 

 beneath it, the flower is termed lateral. Sometimes the first primary axis which proceeds 

 from the embryo terminates in a flower ; but more often the axis continues to grow, 

 or its growth comes to an end, without forming a flower, and it is only lateral shoots of 

 the first, second, or a higher order that terminate in flowers. In the first case the 



* [On this subject see MUller, Befruchtung der Blumen durch Insekten, 1873 ; and Sir John 

 Lubbock, British Wild Flowers in relation to Insects ; also Book III. of this work,] 



