PROPAGATION. 



209 



flowering. Cypripediums, Calantlies, Disas, and a 

 few other terrestrial kinds are a shorter time, gener- 

 ally about three years, before they become strong 

 enough to flower. 



To afford some idea of the delicate nature of seed- 

 ling Orchids, the illustrations in Fig. 5 have been 

 made from living seedlings of Cattleya. No. 1 repre- 

 sents the fruit (natural size) ; No. 2, the seed ; No. 3, 

 a seedling directly after it has emerged from the 

 seed-coats ; No. 4, the same developing the fii'st leaf ; 

 Nos. 5 and 6, seedlings of two and three years re- 

 spectively. From 2 to 6 are all magnified. 



Nepenthes-seeds require the same treatment as 

 Orchids, than which, however, they are quicker to 

 germinate, and form sturdy plants in a much shorter 

 time. The foliage bears tiny pitchers soon after 

 germination. 



Aquatics. — All such plants as Nymphseas, Ne- 

 lumbiums, Sagittarias, and others of aquatic habits 

 may be raised from seed if sown in soil and submerged 

 in water in the light. For seeds of tropical plants 

 a temperature of from 75" to 80* will be necessary ; 

 for the Victoria Begia, So'* will be found none too 

 high. It sometimes happens that seeds of aquatics 

 are sown in soil and treated as for terrestrial plants ; 

 at least, several such mistakes have come to my 

 knowledge. It was thought that the plants liked to 

 gTOw in water only when strong ; which seems about 

 as likely as that fish-spawn should be hatched in dry 

 soil, and the young fishes kept from the water till 

 they had grown a little. 



SPORES OF FERNS. 

 The organs of reproduction in Ferns are quite dif- 

 ferent from those of flowering plants, spores or 

 "Fern-seeds" possessing neither coats, radicle, plu- 

 mule, nor cotyledons such as are found in all true 

 seeds, but nevertheless containing within themselves 

 the capacity to vegetate and produce young Ferns. 

 To distinguish flowering from spore-producing plants 

 the term "acotyledon" (i.i?., without cotyledons) is ap- 

 plied to the latter, and to this group belong all Ferns, 

 Lycopods, Isoetes, Marsilea, Salvinea, Liverworts, 

 and Mosses. Of these the two last are of little horti- 

 cultural interest ; Isoetes, Marsilea, and Salvinea are 

 seldom cultivated except in botanic gardens, but the 

 plants belonging to the first two groups are of 

 great importance as garden plants. To the Ferns 

 and Lycopods therefore, and their modes of repro- 

 duction, and especially to their propagation from 

 spores — an operation of some delicacy —this chapter 

 will be devoted. Before going on to the subject of 

 treatment it may be interesting to say a few words 

 on what is supposed to occur during the vegetation 

 of a Fern-spore. When a spore is placed on any 

 62 



warm, moist medium favourable to its growih, it 

 vegetates by expanding in the form of a tiny thread 

 a simple oblong cell, to which other cells are added, 

 till a thin, green, leaf -like membrane is formed, re- 

 sembling a Liverwort ; this is called a prothallus. 

 The form of this organ varies according to the 

 species, but it is generally kidney-shaped, and about 

 half an inch across. Along the axis of the prothallus 

 fine hair-like roots are developed, by means of which 

 it attaches itself to any moist surface. In addition 

 to these roots there are also produced on the under 

 side of the prothallus little cells, containing tiny 

 coiled threads, which are said to move spontaneously, 

 but most likely owing to the action of moisture on 

 their coiled bodies. These are the fertilising organs 

 analogous to the pollen of an ordinary flower, and 

 called antherozoids. Close to these little bodies other 

 cells are formed on the prothallus, and these contain 

 organs whose functions are precisely the same as 

 those of a pistil of an ordinary flower ; they are 

 called archegonia. As growth proceeds, the little 

 threads or male organs come in contact with the 

 small pistil-like bodies and fertilisation is completed. 

 Soon after this the young Ferns begin to appear, 

 each prothallus producing a single plant, though in 

 a few species several plants are developed from one 

 prothallus. By dividing the prothallus into several 

 pieces each piece will produce a separate plant, as 

 has been proved with Todca superba, the prothallus 

 of which was cut into a dozen pieces, each one of 

 which yielded a plant. The prothallus dies away as 

 the young plants develop roots. It will be seen 

 from this how different the process of spore-vegeta- 

 tion is from that of seeds. A microscope is neces- 

 sary to enable us to perceive the wonderful move- 

 ments of the fertilising organs, and to watch tlie 

 development of a plant from a spore thi'ough all its 

 singular changes. The importance of a knowledge 

 of the above to a Fern-grower will be seen, when it 

 is remembered that some very distinct and useful 

 hybrid Ferns have been raised by crossing two 

 species : as the fertilising process takes place during 

 the development of the plant from the spores, it will 

 be apparent how hybrids are likely to be obtained. 

 Mr. Bause's success in raising hybrid Ferns has been 

 the subject of some surprise even among botanists ; 

 for not only has he produced plants with characters 

 which combine those of the two parents, but every 

 one of his hybrids is fertile and reproduces itself 

 exactly from its spores. Previous to Bause's experi- 

 ments the only Fern we possessed of supposed hybrid 

 character was jidiantum Farleycnsc, which, however, 

 is uniformly baiTen, never producing spores. 



Sterility is much more frequent in cultivated 

 Ferns than is generally supposed. For a large pro- 

 portion of the most popular kinds we are seldom 



