CLASSIFICATION. 



65 



as in the case of seeds. Consequently the spores 

 do not contain hereditary characters combined 

 in their interior, as is the case with all seeds. 

 But when the spore produces a prothallus, and 

 it has attained to maturity, it bears on its under 

 surface male organs called antheridia and female 

 organs called archegonia, which in function at 

 least are in a broad sense analogous to flowers. 



From the antheridia male bodies called zoo- 

 spores are liberated, spiral bodies furnished with 

 eyelash-like cilia, which enable them to move 

 rapidly over wet surfaces. The archegonia are 

 small raised bosses or cones, hollow inside, and 

 containing germ matter. There is a small pore- 

 like opening, permeable to moisture, and into 

 these openings the zoospores find their way, 

 and so fertilization takes place, and the first 

 young fronds of the fern appear. Whereas the 

 fertilization of most flowering plants takes place 

 most readily during dry and fine weather, the 

 cryptogamic plants, on the other hand, can best 

 be fertilized during damp or showery weather. 

 Hence we find all fungoid pests, such as the 

 Potato-disease, for example, increase most rapidly 

 during warm wet weather, when the sperm matter 

 or zoospores can travel most readily (fig. 81). 



It is now apparent how fern hybrids or crosses 

 may be produced now and then in the wild state, 

 and of course much more freely in our ferneries, 

 where many different kinds are grown in close 

 proximity. 



So far as is known, the spiral antherozoids or 

 zoospores act perfectly automatically, running 

 about wherever there is moisture, and so finding 

 their way especially easy on the backs of the 

 prothalli, where the moisture is always being 

 condensed from the ground or wet surface upon 

 which they grow. As these antherozoids run 

 into any pore or crevice where there is moisture, 

 or into any archegonia near to them, it is always 

 possible that the antherozoids of one species may 

 find their way into the archegonia of another 

 kind; and in this manner it is possible for two 

 kinds to be hybridized and for so-called fern 

 hybrids to appear. Those who grow ferns apply 

 this knowledge by sowing the spores of the kinds 

 they wish to hybridize together in a seed-pan, 

 or on any suitable moist surface ; or the spores 

 of many kinds are all mixed and sown together 

 in the same receptacle, so that the chances of 

 their prothalli becoming hybridized are multi- 

 plied indefinitely, as it were. 



Vegetative Sports or Bud Variations. 



Sports are those variations that take place 

 apparently in a sudden and spontaneous manner, 

 vol. i 



and have long been a source of wonder and 

 speculation to gardeners and others, and the 

 exact cause of their simultaneous outburst still 

 remains a mystery. Some botanists consider 

 them due to the unequal divisions of the nucleus 

 of the cell, while others look on all garden plants 

 as being in a high state of tension, of which the 

 balance is now and then disturbed by unknown 

 causes, so that the variety slides back wholly, 

 or in part, along its genealogical line. In this 

 case "sports" may be due to "atavism", or the 

 "throwing back" to ancestral forms. 



"All the different branches, or even joints, 

 of any plant are, in a very important sense, 

 distinct individuals, since every one develops 

 its own organs, each is capable of reproducing 

 itself independently, and each is unlike every 

 other because it is acted upon differently by 

 environment and food-supply. It is not strange, 

 therefore, that some of these individuals should 

 now and then depart very widely from the 

 ordinary type, and thereby attract the atten- 

 tion of a gardener who would forthwith take 

 cuttings or grafts from the part. Every branch 

 is a bud variety, just as truly as every seedling 

 is a seed variety, and there should be no greater 

 mystery connected with the sports of buds 

 than there is with the variations from seeds, 

 for the causes which produce the one may be, 

 and are, equally competent to produce the 

 other" (L. H. Bailey). 



Sports are common in the case of plants that 

 have been much cross-fertilized in the garden. 



[f. w. b.] 



CHAPTER X. 



CLASSIFICATION. 



Species — Genera — Orders — Classes — Genealogical 

 Arrangements — Artificial Groups. 



In dealing with a large number of ideas, facts, 

 or objects, some mode of classification becomes 

 needful in order to facilitate research. There 

 are two modes of classification, which may be 

 broadly termed the artificial and the natural 

 systems. In an artificial system the objects are 

 arranged in any manner that may be convenient, 

 without reference to the history, nature, or con- 

 struction of the objects. An alphabetical index is 

 an illustration of an artificial system of classifica- 

 tion. The words in such an index are arranged 

 in alphabetical sequence without the least refer- 

 ence to their significance. But if the words 

 relating to gardening were all collected together 

 under one heading, those relating to chemistry 



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