Morphology of the Citrus. 195 



call seed, but multiplied only by a sort of division of 

 some of their parts, as inferior animals do, even at the 

 present day, or by what are called spores, such as those 

 of ferns and fungi. The latter have the advantage of 

 flotation in the air, so that they may be carried to long 

 distances, but, on the other hand, they require special 

 conditions for starting into life. They cannot with- 

 stand unfavourable surroundings so well as ordinary 

 seeds can. Spores may be floating in the atmosphere 

 everywhere, but nothing comes of them, as the con- 

 ditions for germination and sustenance of life are 

 wanting. 



Later on, possibly, may have commenced the multi- 

 plication of plants by buds on their roots, and on 

 underground stems, and finally by buds on the stems 

 which rise into the air. The stem bud, or as it might 

 be called, the bark bud, is probably the ancestral form 

 of the seed bud, which we find in the fruit. From the 

 bark, where it usually occupies the axilla of the leaf, or 

 other representative of the leaf, we may trace it to the 

 edge of the leaf,* in the angles (abortive axillae), formed 

 by the crenations (abortive -leaflets), as in the Bryo- 

 phyllum calycinum. Hence we can finally follow the 

 bud to the edges of the curled up carpel, or modifica- 

 tion of the leaf, such as the pea pod, or the pulp quarters 

 of an orange or lemon in what we call the seed. 



The ripe seed of the fruit is then the finished article,, 

 furnished with an independent bud. It has moreover,, 

 as I said, a small store of food to sustain it, while it is 

 perfecting its organs of nutrition the roots and the 

 leaves. The whole is furnished with coverings, which 

 usually very efficiently protect the emancipated bud, 

 and its store of food. The efficiency of the seed 



' f The leaf, as I have stated in another place, I would consider a 

 modified branch. 



O 2 



