REPRODUCTION. 599 



buds. In Lichens, for instance, there are the soredia, which 

 are minute buds containing both algal and fungal cells ; these 

 are formed in large numbers on the thallus, and each is 

 capable of developing into a new thallus. Among the Algae, 

 there are \.\\Q gemmcz of the Sphacelariae, the "propagula" of 

 some Florideae, and in the Characeae the bulbils or "starch- 

 stars" of Cham stelligera, which are underground nodes, the 

 branches with naked base and the proembryonic branches found 

 by Pringsheim on old nodes of Chara fragilis. In the Mosses, 

 small tuberous bulbils frequently occur on the rhizoids, and 

 in many cases (Bryum annotinum, Aulacomnion androgymim, 

 Tetraphis pellucida, etc.) stalked fusiform or lenticular gemmae 

 containing chlorophyll are produced on the shoots, either in 

 the axils of the leaves or in a special receptacle at the summit 

 of the stem. Gemmae of this kind are also produced in large 

 numbers in special receptacles on the thalloid stem of Mar- 

 chantia (see fig. 49, p. 426) and Lunularia among the Liver- 

 worts, as well as by the prothallia of some Ferns. In many 

 cases (Nep/irolepis tuber osa, Lycopodium, Lilium bulbiferum, 

 etc.), the buds borne on the shoot become swollen and filled 

 with nutritive substances, constituting bulbils, which, when 

 they fall off and germinate, give rise to new plants. In a few 

 plants adventitious buds are formed which subserve vegeta- 

 tive propagation. In Bryophyllum Calycinum (Crassulaceae) 

 and many Ferns (Nephrodium (Lastrced) Filix mas, Asple- 

 nium (Athyrium] Filix fcemina, and other species of As- 

 plenium), such buds are formed on the leaves. A curious 

 case of this has been observed by Strasburger in Ccelebogyne 

 ilicifolia, Funkia, Citrus, and Nothoscordum fragrans. In 

 these plants adventitious budding takes place from the cells 

 of the tissue of the nucellus which leads to the appearance of 

 one or more embryos in the embryo-sac. The most familiar 

 instance of reproduction by means of buds is afforded by the 

 bulbous plants. These plants are annuals, and each during 

 its life produces at least one modified subterranean bud, 

 termed a corm or a bulb, from which a new plant is developed 

 in the succeeding year. Other organs may also be modified 

 to subserve vegetative propagation. Thus, the Potato-plant 



